Calculating Sustained Yield for the
Forest Management Plan (2004-2013)
STAGE 3 Report
Report for the Conservation Commission of
Western Australia by the Independent Panel
June, 2003
I. Ferguson, M. Adams, J. Bradshaw, S. Davey,
R. McCormack, J. Young
ii
EXECUTIVE SUMMARY
1. Introduction
The terms of reference for this Stage 3∗ review require that
“The Panel will provide a written report to the Conservation Commission, based on the data,
assumptions, methods and Interim Proposed Forest Management Plan as at a date specified by
the Commission, that confirms whether:
The sustained yield levels calculated for defined forest types are consistent with:
1. Findings of the Stage 1 report and outcomes of the recommendations
2. The area of forest that is proposed to be available for timber harvesting
3. The practices that are to be used to provide timber harvesting for ecologically sustainable forest
management, as set out in the draft Forest Management Plan, and
4. The data, assumptions and methods used, and
5. The calculations have been carried out objectively and in an operationally realistic manner.”
2. Forest areas and maps
The stratification of the jarrah forest has been revised and most of the karri forest has a new stratification
from large scale aerial photos. The Geographic Information System is excellent. The Panel conducted
spot checks of its capacity to accurately reflect the areas of the various strata and is satisfied that it is very
accurate. The Panel is satisfied that the stratification and mapping systems are sufficiently accurate and
robust for the calculation of sustained yield. Well developed protocols exist for checking and correcting
apparent errors in species or structural typing. Appropriate small allowances are made in calculating the
sustained yield for the impact of these errors based on the historical experience of corrections. In
summary, such errors have no significant effect on the overall capacity of the system to properly and
accurately calculate the sustained yield.
3. Inventory
The Panel considers that the design of the jarrah inventory system represents Australian best practice, and
that with the adjustments described later, provide inventory estimates at an appropriate level of precision
and confidence for strategic yield scheduling. However, during the course of the life of the Plan, new
field sampling will be required to update it. In addition, more attention needs to be given to monitoring
the predicted and actual values from harvesting forest. The Panel therefore recommends that during the
life of the Plan, greater emphasis is placed on increasing the sampling framework for monitoring, and
extending the analysis of monitoring data to separate any inventory bias from the utilisation factor. Given
the expected changes to utilisation that will evolve with the re-structure of the industry and the time
required to accumulate sufficient sampling we do not consider that adjustment to the yield is likely to be
required before the next revision of the Plan.
The Panel has been advised that the largest source of difference between the estimate and sawlog
acceptance is in trees that are made available for harvest but are left standing, rather than the full
utilisation of felled trees. This suggests that more attention is required to ensure that potentially suitable
sawlog trees (albeit marginal) are felled and utilised.
A new karri inventory system is in place using the same design as in the jarrah forest and therefore also
represents Australian best practice. Current allowances for relating predicted to actual volumes are
adequate, pending the likely progressive shift in utilisation standards as more regrowth is logged, while
recognising that they are likely to be conservative. A greater emphasis on monitoring predicted against
actual volumes is essential during the life of the Plan in the light of changing log sizes and grades.
However, it is likely that karri will present fewer problems than jarrah with respect to the felling and
utilisation of potentially suitable sawlog trees.
In summary, the inventory base is very good and the residual risk posed by possible mismatching of
predicted and actual volumes is now small. The jarrah inventory is nearing the end of its useful life but its
∗
This report is the third produced by this Panel following the Stage 1 report completed in April 2001
(Ferguson et al., 2001a) and the progress report produced in September 2001 (Ferguson et al., 2001b).
iii
use without updating for growth in two-tiered and irregular stands subsequent to 1990 introduces a
significant element of conservatism.
Recommendation 1
In refining the inventory during the life of the Plan, greater emphasis should be placed by the Department
of Conservation and Land Management on increasing the sampling framework for monitoring, and
extending the analysis of monitoring data to separate inventory bias from the utilisation factor, in
addition to updating the field sampling.
4. Growth
The Panel believes that the growth estimates that have been used are robust and appropriate for the
estimation of sustained yield in this plan.
The precision of the output from the JARSIM model can be improved over time in several ways:
•
Utilising more data as they become available from younger stands over a greater range of sites, as a
basis for initialising the model;
• Improving the estimates of stand condition following thinning as a result of post thinning monitoring;
• Improving the understanding of forest dynamics by further research on the response to multiple
thinnings;
• Reviewing the existing framework of growth plots and establishing new plots in stands that more
closely represent the structure of future stands.
Significant improvement in the available data cannot be achieved for at least a decade and there is little
value in further development of the growth model until that is available.
The Panel is of the view that growth and future condition of the karri forest has been estimated at a
precision appropriate for sustained yield calculation and that the process is robust. The precision of the
model will progressively improve as more data become available over time.
The predicted future stand condition before and following the simulated harvest are recorded for each
simulation run, providing satisfactory transparency of the assumptions made.
Recommendation 2
In refining the growth models over the life of the Plan, the Department of Conservation and Land
Management should adopt a strategic approach and seek to obtain data from a broader range of ages
and conditions as those opportunities become available. Major refinement of the growth models is
therefore unlikely to be feasible until towards the end of the Plan period.
5. Forest Health
The Forest Management Branch within the Department of Conservation and Land Management has made
extra-ordinary progress in collating data on and in analysing the rate of dieback spread. Hence the
recommendations of the expert working group established to design a trial of the protocol for dieback
management may require further review.
The new information on impacts of dieback on jarrah sustained yield demonstrates the importance of
minimising disease spread into potential moderate impact areas of forest.
The maps of projected spread of Phytopthora cinnamomi will assist decision making in a range of policy
and management areas with respect to future impacts of dieback, not only on wood flows, but also
biodiversity and ecosystem health and vitality. The methods developed have great potential in the
definition of “protectable areas” and the setting of priorities for management in a range of ecosystems,
regardless of tenure. The Panel identified a need for further commitments on dieback management, and
hence the mapping of infections, within the conservation estate.
The new simulation and mapping system also has the potential to be a powerful tool in demonstrating the
effects of random infections on areas currently free of disease. This should be encouraged as it would be a
useful way of demonstrating the consequence of poor hygiene on future spread. Best practice with regard
to minimising dieback impacts is dependent on the use of this simulation and mapping system and its
further refinement over time.
An earlier recommendation of the Environmental Protection Authority was that results of past monitoring
of dieback spread and occurrence should be collated and made public. The Department of Conservation
and Land Management now have material in a form that can be finalised for distribution.
The findings and predictions of the Department of Conservation and Land Management research project
should be used to assist in the implementation of a number of the recommendations stemming from
iv
Environmental Protection Authority Bulletin 1010 and related reviews. While much has been done in
developing these for the management of the productive forest, they merit revision in the light of this new
information. In addition, the Panel is especially concerned that little appears to have been done in
developing management prescriptions specific to the conservation reserves concerned. In the light of this
recent research, this represents a significant risk to biodiversity.
Recommendation 3
Department of Conservation and Land Management resources should ensure that disease status of
‘uninfested’ areas in both production and conservation areas is monitored adequately and reported
separately for the production forest and reserves, with amendment of Key Performance Indicator 14 in
the Interim Proposed Forest Management Plan accordingly.
The results of research relating to the spread and impact on jarrah growth of dieback should be
(i) promulgated in an appropriate form to the Western Australian community by the Department of
Conservation and Land Management.
(ii) used to assist the implementation of Environmental Protection Authority and related
recommendations on the management of the productive forest and especially on the management of
conservation reserves.
The Department of Conservation and Land Management should ensure that the new dieback spread and
impact models are further developed, especially to model the effects of random or new infections in areas
of differing potential impact, and that Objective 13 of the Interim Proposed Forest Management Plan be
amended accordingly to incorporate the action.
6. Selecting and applying silvicultural treatments
The Panel noted that the predicted versus actual outcomes of silvicultural treatments are to be closely
monitored for the period of the plan and recorded in the silvicultural information system, SILREC.
Consistent and significant differences between assumed and the implemented silviculture could have long
term consequences to the projection of sustained yield and hence future adjustments may be required
resulting from such monitoring.
Balanced Silviculture
The Panel is in agreement with Burrows et al. (2002) that the silvicultural system has to be designed
within a broad ecological base to deliver ecologically sustainable forest management. Silvicultural
guidelines need to be able to cater for non-wood values to enable appropriate silvicultural decisions to be
made. Silvicultural decisions and practices can greatly change the forest structural and floral composition
spatially and through time resulting in differential supply streams of ecosystem services and products
(including water and biodiversity). It is important that the Plan contain clearer forest ecosystem objectives
and guidelines that inform silvicultural decisions. Ecologically sustainable forest management is
fundamentally about protecting the ecological integrity (biodiversity, health and productivity) of forest
ecosystems while sustaining a supply of products and services to the community (Burrows et al. 2002).
The Panel believes that the current Interim Proposed Plan still lacks (see Stage 1 Recommendation 4.1)
clear objectives that enable trade-off decisions to be made in the context of forests at a whole-of-forest,
landscape, forest patch (block) and coupe scales through appropriate modifications to rule sets. Such
objectives are required for looking at consequential impacts on wood and non-wood values and potential
effects on sustained yield during the period of the plan. Hence the Panel recommends that the
Conservation Commission provide explicit whole-of-forest and landscape objectives and targets that
address these trade-offs.
Fauna habitat zones and structural goals
The Plan needs to clearly articulate the objectives, role and purpose of Fauna Habitat Zones as they are
currently unclear in the Interim Proposed Plan. The Panel understands that the purpose of the zones is to
assist species to recolonise adjacent regrowth forest as well as maintaining throughout the forest fauna
that depend on forest habitat characteristics that may be adversely affected by forest operations. Hence
Zones have a quite complementary purpose to forest set aside in formal and informal reserves.
These Zones may be placed on longer rotations or subjected to conservative logging with the objective of
v
managing primarily for faunal habitat characteristics while allowing the removal of sawlog as a secondary
objective. With appropriate training of Department of Conservation and Land Management and Forest
Products Commission staff and clear specification of objectives, these forests could be managed for both
fauna habitat and/or understorey flora and sawlogs, so fulfilling Objective 7 of the Interim Proposed Plan.
Silvicultural prescriptions
The Panel concluded that there has been a thorough review of the Jarrah Silvicultural Guidelines giving
appropriate attention to regeneration adequacy, the maintenance of flora diversity and fauna habitat.
With regard to measures to ensure that the levels of tree removal do not result in increased salinity in
streams emanating in the intermediate rainfall zone the conclusion of the Burrows Panel is endorsed by
the Panel. They found “no basis by way of new evidence for changing” the measures that have been
current during the last decade but noted that new data may become available from a major current
catchment study under-way in the northern jarrah forest.
The Panel is aware that there has been considerable discussion of water quality issues during plan
development based on a report from the Waters and Rivers Commission (2001). A number of guidelines
for the management and maintenance of the stream-zone informal reserves will be reviewed during the
first half of the plan. A program for any change will be reported in the mid-term review of the Plan. The
Panel was satisfied with this approach and considered that this flexibility did not present a risk to
sustained yield based on the current allowances. Major increases of stream zone informal reserves are not
envisaged.
The Karri, Jarrah and Wandoo Silvicultural Guidelines to be used have recently been reviewed and the
residual risk to sustained yield of further changes being required is low.
The risk to sustained yield through marri being retained due to a future lack of markets has been directly
incorporated into the woodflow scheduling.
Recommendation 4
The Conservation Commission should
(a)
provide explicit whole-of-forest and landscape objectives and targets to help address
the trade-offs between wood and non-wood values at the various planning scales.
(b)
clearly articulate the objectives and targets of Fauna Habitat Zones in the Forest
Management Plan.
(c)
review the selection criteria for the Fauna Habitat Zones in the light of the above.
7. Providing for risks
The Panel examined a number of factors that posed potential hazards to the calculation of sustained yield
and on ecologically sustainable forest management. These included:
•
•
•
•
•
•
•
•
•
Fire
Fungal disease (Armillaria, P. cinnamomi)
Insect attack
Immediate climate (frost, drought and waterlogging)
Longer term climate change
Salinity
Forest area loss and conversion
Management practice and implementation
Data uncertainty
The Panel concluded that, with the exception of two matters that are the subject of recommendations to
reduce risks, the residual risks posed by these hazards were low and well catered for by the systematic
conservatism inherent in the calculation of sustained yield and ongoing monitoring.
Recommendation 5.
Further refinement of the expected scheduling of jarrah regrowth thinning should be undertaken during
the period of the Plan by the Department of Conservation and Land Management.
Any proposals for significant changes in zoning or operational guidelines that affect harvestable areas
must be accompanied by a re-estimation of sustained yield by the Department of Conservation and Land
Management to allow evaluation of impacts on ecologically sustainable forest management values.
vi
8. Scheduling and management of logging
The Panel believes that the systems employed to simulate long-term woodflows (FORSCHED and its
supporting systems) are appropriate and robust for the purposes of long term yield projection of jarrah
and karri forests. The Panel has also investigated the operation of the systems and reviewed the derivation
of the conversion factors. It is satisfied that the system produces adequate estimates of utilisable yield for
the planning period.
The Panel is concerned that consideration is being given to letting contracts in which the annual cut is
solely Grade 1 sawlog. There are concerns that some associated Grade 2 sawlog might be left on the
forest floor. To the extent that this may occur, it constitutes a risk to the sustained yield in that monitoring
of the actual cut for the period of the Plan could be inaccurate, relative to its definition. In short, more
Grade 1 and 2 sawlog may effectively be being cut than would be apparent from records of sales.
The Panel believes that it may be preferable that all sawlog contracts be allocated and monitored on the
basis of the volume to 200 mm top diameter combining Grade 1 and Grade 2 for the purposes of yield
regulation and providing for all sawlog harvesting to be based on ‘run-of-bush’ i.e. harvesting all sawlog
products from the forest in whatever ratio it occurs. Differential prices could still be applied for different
log sizes and grades within that definition if required, but this change would remove an otherwise
unrecognisable source of error in the regulatory system and assist transparency.
The Panel notes that there are many factors involved in ensuring that all utilisable yield is recovered from
logging coupes. Waste at the coupe level could lead to pressure to extend harvesting areas to meet volume
commitments, reducing long term sustainable yield. Forest Products Commission staff and the harvesting
operatives play a key role. Ongoing development of the procedures and processes used to monitor
utilisation and the effective conversion level is needed by Department of Conservation and Land
Management and the Forest Products Commission to ensure waste is minimised. Comparison with preharvest forecasts of available volumes for an individual coupe can provide only a guide because these are
generated from stratum wide data and cannot reflect the specific circumstances of each coupe. However,
periodic data collected at the annual or three year level should be monitored by the Department of
Conservation and Land Management and Conservation Commission as a basis for management and
review.
Recommendation 6
Contracts let by the Forest Products Commission for the supply of sawlogs should be based on the
volume to a 200mm top diameter, using current specifications to the lower limit of Grade 2. This will
improve consistency and transparency of the level of removals against sustained yield calculations.
Within three years the Department of Conservation and Land Management should develop systems to
monitor and report on differences between predicted yields and actual harvest volumes. These should be
reported on annually.
9. Calculating sustained yields
The Panel used the scenario outlined in Appendix 15 of the Interim Proposed Forest Management Plan
(which has come to be referred to as Scenario D) as the basic reference for the calculation of sustained
yield (see Appendix 1 for detail).
The Panel examined the processes used in modelling and simulating sustained yield and concluded that
they were robust. Provided the settings prescribed are appropriate to ecologically sustainable forest
management, the Panel is confident that the calculation of sustained yield will be appropriate and
sufficiently conservative for the purpose, given ongoing monitoring of conditions.
The Panel noted that the initial estimates of sustained yield for Scenario D had not been able to include
the newly developed research and modelling of dieback spread and impact. The Panel regards this work
as fundamental and would not be willing to confirm that any option would meet the criteria for
ecologically sustainable forest management if it omitted this use of this modelling.
The Panel therefore examined a number of other options. These included an alternative definition of
Fauna Habitat Zones, a variation to the proposed reservations that would provide access to regrowth and
two-tiered forest within newly proposed reserves, the effect of shorter rotations, and delaying early
thinning of jarrah regrowth. The Table which follows summarises the outcomes.
The Panel favours a scenario incorporating a combination of these options. Yield loss from dieback must
vii
be incorporated. The Panel believes that much of the thinning of jarrah will be delayed unless the
Government is prepared to subsidise it and hence the majority of this impact will be felt whatever other
modifications are selected. Shorter rotations should be confined to the more productive jarrah forest (i.e.
other than eastern jarrah). Only that regrowth and two-tiered forest in Dalgarup and parts of other newly
proposed reserves that are readily accessible and of low conservation value should be included.
Local expertise is required to define this option in detail, so we cannot confirm the sustained yield for it.
Nevertheless, it clearly represents a balance that meets almost all of the major underlying concerns and
values. Almost every interest group will claim that it does not achieve its particular goals but the Panel
would argue that, in aggregate, it is likely to achieve a higher level of social net benefit than any one of
the preceding options or of those most favoured by individual interest groups. That is the essence of
trade-offs at the whole-of-forest level.
The Panel is satisfied that ample marri resource exists to support a substantial cut of residual wood, if
markets are available, and to supply current sawlog demands.
Table 9.1. Sustained yields for scenarios and detailed options.
Scenario / Option
Sustained yield (m3/y)
Jarrah
Karri
Scenario D*: Reference scenario
D (a) No allowance for dieback spread
D (b) Allowing for dieback spread
D(c) Allowing for dieback spread, delayed thinnings
D (d) Allowing for dieback spread, shorter rotations
135,000
116,000
111,000
126,000
50,000
50,000
50,000
53,000
126,000
124,000
138,000
52,000
52,000
56,000
139,000
133,000
151,000
74,000
74,000
78,000
Panel Option 1:Alternative fauna habitat zones
1(a) Allowing for dieback spread
1(b) Allowing for dieback spread, delayed thinnings
1(c) Allowing for dieback spread, shorter rotations
Panel Option 2: Access to regrowth/two-tiered areas
2(a) Allowing for dieback spread
2(b) Allowing for dieback spread, delayed thinnings
2(c) Allowing for dieback spread, shorter rotations
* Scenario D is defined in the Interim Proposed Forest Management Plan Appendix 15 and provided to
the Panel as the basis for assessment.
The Panel re-iterates that it is confident that the table setting out the levels of sustained yield for various
options is robust and the values are conservative. It is also confident of the system’s flexibility and
capacity to accommodate appropriately most major variations to those settings.
Each of the scenarios and options evaluated provide different levels of contribution to socio-economic
values and biological conservation. The Panel is of the view that a combination of options 1 and 2 will
meet both the biological and other components of ecologically sustainable forest management to a
satisfactory level.
10. Other matters
Improving transparency
The Panel notes the considerable effort put in to improving transparency during the period of the period
of development of the 2004-2013 Forest Management Plan and these are commended.
The Panel notes a strong emphasis on the reporting of audit results and other compliance measures and
the objectives for a mid-term review and consequent reporting. Effective communication with the
broader community is also needed on more general forestry performance in relation to progress toward
achievement of Ecologically Sustainable Forest Management.
The Panel urges that new resources be found to support public education and dissemination (including
peer-reviewed publication) programmes.
viii
Relationship to Regional Forest Agreement
The Panel is concerned about how the Regional Forest Agreement relates to the Forest Management Plan
given the establishment of the Regional Forest Agreements Act 2002 and the consequential obligations
resulting from the Western Australian Regional Forest Agreement. This concern results from how
commitments made in the Regional Forest Agreement flow from international obligations through the
Commonwealth legislation (Environment Protection and Biodiversity Conservation Act 1999; Regional
Forest Agreements Act 2002) and national policy (National Forest Policy Statement) to the State’s Forest
Management System and in particular the Management Plan.
Western Australia agreed in the Regional Forest Agreement “to produce and publish a Forest
Management Plan to implement the commitments of this Agreement” (Clause 43). The Commonwealth
or other stakeholders may have concerns that the resource base for which sustained yield is calculated is
not consistent with the resource base commitments of the Regional Forest Agreement, or that Western
Australian forest policy is not consistent with the policy settings and commitments agreed to in the
Regional Forest Agreement. This raises issues concerning the possibility of legally enforceable rights and
obligations that are outside the expertise of the Panel.
Future determination of sustained yield
In the calculations of the sustained yield by the Department of Conservation and Land Management, the
assumption is made that non-declining yield is pivotal to the long term sustainability of the forest.
However, reliance on the control of sustained yield of sawlogs alone is a simplistic device when the
intention is to sustain all values. There is no pre-emptive priority for wood over non-wood values or vice
versa. There may need to be an initial array of varying and independent priorities set for all values in the
form of individual structural goals. If a feasible and near-optimal solution cannot be found that satisfies
all these initial structural goals then the nature of the subsequent trade-offs required between goals must
become transparent. The present process obfuscates these trade-offs but cannot ultimately avoid them, as
the present report shows. New approaches based on setting and managing toward structural goals and
ecological management can be developed. The effect of this approach in forestry is to shift the emphasis
to the sustainability of forest and landscape structure and values, and away from a reliance on nondeclining yield of sawlogs as the primary regulator of sustainability.
The Panel is of the view that this new approach to the determination of sustained yield could result in
greater benefits to both conservation and socio-economic values than does the rigid application of the
current mechanisms. At the same time it would provide improved transparency of the mechanisms
employed to achieve ecologically sustainable forest management.
The Panel recognises that such an approach would require more rigorous whole-of-forest and landscape
level analyses, which would depend on data sets and approaches that need to be refined and expanded.
This will take some time. Sufficient data are not likely to be available until prior to the next revision of
the Forest Management Plan in 2014. Extensive consultation would also be necessary to build consensus
to support the approach.
Recommendation 7
The Panel recommends that alternative approaches be developed to determine the sustainable yields of a
range of forest values while maintaining critical elements of ecosystem function. This should incorporate
direct approaches to maintain target forest structures, and should be investigated and subjected to
thorough analysis during the life of the plan.
ix
Table of Contents
1
2
3
4
5
6
7
INTRODUCTION.............................................................................................................................. 1
1.1
Background.................................................................................................................................. 1
1.2
Terms of reference of current review........................................................................................... 1
1.3
Underpinning principles............................................................................................................... 2
1.4
Outcomes of previous reviews..................................................................................................... 3
1.5
Risk assessment and management ............................................................................................... 3
FOREST AREAS AND MAPS ......................................................................................................... 4
2.1
Introduction.................................................................................................................................. 4
2.2
Formal reserves............................................................................................................................ 4
2.3
Informal reserves ......................................................................................................................... 4
2.4
Stratification and maps ................................................................................................................ 4
Conclusions ........................................................................................................................................ 5
INVENTORY .................................................................................................................................... 6
3.1
Jarrah............................................................................................................................................ 6
Conclusions ........................................................................................................................................ 6
3.2
Karri............................................................................................................................................. 7
Conclusions. ....................................................................................................................................... 7
3.3
Recommendation ......................................................................................................................... 7
GROWTH .......................................................................................................................................... 8
4.1
Jarrah............................................................................................................................................ 8
Dieback-affected forest ...................................................................................................................... 8
Regrowth forest .................................................................................................................................. 8
Gross checks....................................................................................................................................... 8
Conclusions ........................................................................................................................................ 9
4.2
Karri............................................................................................................................................. 9
Conclusions ........................................................................................................................................ 9
4.3
Recommendation ......................................................................................................................... 9
FOREST HEALTH .......................................................................................................................... 10
5.1
Introduction................................................................................................................................ 10
5.2
Dieback disease.......................................................................................................................... 10
Effects of dieback on sustained yield. .............................................................................................. 10
Conclusions ...................................................................................................................................... 12
5.3
Recommendation ....................................................................................................................... 13
SELECTING AND APPLYING SILVICULTURAL TREATMENTS .......................................... 14
6.1
Introduction................................................................................................................................ 14
6.2
Achieving balance...................................................................................................................... 14
6.3
Fauna habitat objectives and structural goals............................................................................. 15
6.4
Silvicultural prescriptions .......................................................................................................... 17
Jarrah................................................................................................................................................ 17
Salinity ............................................................................................................................................. 17
Water quality.................................................................................................................................... 17
Regeneration .................................................................................................................................... 17
Research ........................................................................................................................................... 17
Karri ................................................................................................................................................. 18
Marri retention ................................................................................................................................. 18
Trade-offs......................................................................................................................................... 18
Fauna habitat zones and structural goals .......................................................................................... 18
Silvicultural prescriptions................................................................................................................. 19
Conclusions ...................................................................................................................................... 19
6.5
Recommendation ....................................................................................................................... 19
PROVIDING FOR RISKS............................................................................................................... 20
7.1
Fire............................................................................................................................................. 20
7.2
Disease....................................................................................................................................... 20
7.3
Insects ........................................................................................................................................ 21
7.4
Immediate climate...................................................................................................................... 21
x
Salinity....................................................................................................................................... 21
7.5
7.6
Silvicultural practice .................................................................................................................. 21
Variation from prescription .............................................................................................................. 21
Failure to implement scheduled follow-up silviculture. ................................................................... 21
7.7
Loss of productive forest area.................................................................................................... 22
7.8
Long term climate change.......................................................................................................... 22
Conclusions ...................................................................................................................................... 23
7.9
Recommendation ....................................................................................................................... 23
8
SCHEDULING AND MANAGEMENT OF LOGGING................................................................ 24
8.1
Yield forecasting........................................................................................................................ 24
8.2
Log yields .................................................................................................................................. 25
8.3
Changes to log description......................................................................................................... 25
8.4
Minimum viable logging volumes ............................................................................................. 26
Conclusions ...................................................................................................................................... 26
8.5
Recommendation ....................................................................................................................... 27
9
CALCULATING SUSTAINED YIELDS ....................................................................................... 28
9.1
Introduction................................................................................................................................ 28
9.2
Sustained yield........................................................................................................................... 28
9.3
Jarrah and Karri sustained yield options .................................................................................... 28
Dieback spread ................................................................................................................................. 29
Option 1: Alternative Fauna habitat zones ....................................................................................... 29
Option 1b: Delayed thinnings........................................................................................................... 29
Option 1c: Shorter rotations ............................................................................................................. 29
Option 2: Access to two-tiered and regrowth in proposed reserves. ................................................ 29
Conclusions ...................................................................................................................................... 32
10 OTHER MATTERS......................................................................................................................... 33
10.1
Improving transparency ......................................................................................................... 33
10.2
Relationship to the Regional Forest Agreement .................................................................... 33
10.3
Future determination of sustainable yields............................................................................. 34
10.4
Recommendation ................................................................................................................... 35
11 REFERENCES................................................................................................................................. 36
12 APPENDIX 1 ................................................................................................................................... 39
13 APPENDIX 2 ................................................................................................................................... 42
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1
INTRODUCTION
1.1
Background
This review had its origins in commitments contained in the report by Mr Mike Codd of January 1999
and the Regional Forest Agreement (RFA) of May 1999. The report by Mr Codd included the following
statement:
“it is acknowledged that the RFA process will establish an expert panel to provide
independent scientific advice on the provisional sustained yield figure consistent
with the principles of ecologically sustainable forest management, and with
appropriate provision for potential improvements in utilisation; with such a panel
expected to take some 12 months to report”
Clause 50 of the Regional Forest Agreement of May 1999 stated:
“The Commonwealth accredits the process described in An Appraisal of Methods and Data used
by Department of Conservation and Land Management to Estimate Wood Resource Yields
for the South-West RFA Region of Western Australia (Turner B.J., Department of Forestry,
Australian National University, December 1997) and being used by Department of
Conservation and Land Management in the calculation of Sustained Yield of wood products
from the public native Forest and plantation estate on the understanding that the
improvements recommended in that report will be addressed prior to the development of the
next Forest Management Plan. Western Australia agrees that the methods and data to be
used in the calculation of the Sustained Yield of wood products from the public native
Forest and the Sustained Yield figures to be included in the Forest Management Plans will
be reviewed by a panel of suitably qualified independent experts as part of the development
of each Forest Management Plan under the Conservation and Land Management Act and
improvements incorporated during the Forest Management Planning process. Western
Australia confirms that its current standard of inventory will be maintained and yield and
planning databases and systems, as amended by this Agreement, will be enhanced.”
The purpose of the so-called Stage 1 review completed in April 2001 (Ferguson et al., 2001a) was to fulfil
the above requirements and to facilitate the development of the next Forest Management Plan.
A brief Stage 2 progress report (Ferguson et al., 2001b) dealt with progress relating to the calculation of
sustained yield to September 2001. The Panel could not complete its terms of reference because a number
of critical matters concerning areas of reserves and silvicultural guidelines had not been completed.
1.2
Terms of reference of current review
The terms of reference for this Stage 3∗ review require that
“The Panel will provide a written report to the Conservation Commission, based on the data, assumptions,
methods and Interim Proposed Forest Management Plan as at a date specified by the Commission, that
confirms whether:
The sustained yield levels calculated for defined forest types are consistent with:
1. Findings of the Stage 1 report and outcomes of the recommendations
2. The area of forest that is proposed to be available for timber harvesting
3. The practices that are to be used to provide timber harvesting for ecologically sustainable forest
management, as set out in the draft Forest Management Plan, and
4. The data, assumptions and methods used, and
5. The calculations have been carried out objectively and in an operationally realistic manner.”
∗
This report is the third produced by this Panel following the Stage 1 report completed in April 2001
(Ferguson et al., 2001a) and the progress report produced in September 2001 (Ferguson et al., 2001b).
1
1.3
Underpinning principles
As noted in the Stage 1 report (Ferguson et al. 2001a), the agreed principles of Ecologically Sustainable
Forest Management set out in the Terms of Reference of the review are:
•
•
•
•
•
•
•
•
planning and management of forests should maintain the suite of forest values for
present and future generations:
maintain and enhance long-term multiple socio-economic benefits to meet the needs
of societies;
protect and maintain biological diversity;
protect and maintain natural and cultural heritage;
maintain the productive capacity and sustainability of forest ecosystems;
maintain forest ecosystem health and vitality;
protect soil and water resources;
maintain forests’ contribution to global carbon cycles; and
(b) planning and management of forests should be guided by the precautionary principle;
(Regional Forest Agreement: Attachment 5)
A discussion of these principles may be found in the Ecologically Sustainable Forest Management report
of the Regional Forest Agreement. The precautionary principle is defined thus:
“Where there are threats of serious or irreversible environmental damage, lack of full
scientific certainty should not be used as a reason for postponing measures to prevent
environmental degradation. In the application of the precautionary principle, public and
private decisions should be guided by
I.
careful evaluation to avoid, wherever practicable, serious or irreversible damage to the
environment;
II.
an assessment of the risk-weighted consequences of various options.”
The principles of Ecologically Sustainable Forest Management state that planning and management
should maintain the full suite of forest values for future and present generations through a set of principles
relating to the management of various of those values. Sustainability for future generations is clearly a
key factor that addresses the equity of resource use between generations. Mention of the long-term
multiple socio-economic benefits makes it clear that the review is not confined to commercial net
benefits. All values or uses have to be considered in addressing both the equity and efficiency of
sustainable resource use.
The role of the Panel is to try to ensure that management practices maintain or enhance particular forest
values listed in the set of principles for Ecologically Sustainable Forest Management, so that the
Conservation Commission and Government can then choose outcomes that make the totality of the social
net benefits across the entire forest as high as possible. As is well-known, neither the available data nor
analytical techniques are equal to solving this task analytically, and hence the use of a panel of experts,
supplementing these endeavours with public input to identify areas of concern and possibly needing
further action or change.
Sustainability has been defined as the capacity for continued productivity where the primary requirement
is for site and soil protection and for adequate regeneration and protection and sustainable yield as the
capacity to maintain relatively consistent levels of production or products over an extended period. In the
case of Western Australia, the Conservation and Land Management Act 1984 refers to ‘sustained yield’ in
exactly the same context as sustainable yield, and the Panel therefore uses the term ‘sustained yield’ to be
consistent with the legislation and terms of reference, but noting that it regards its definition as being
identical to that for sustainable yield.
2
The Conservation and Land Management Act 1984 explicitly states several goals for forest management
in Western Australia that are broadly compatible with the principles of Ecologically Sustainable Forest
Management. In its Stage 1 report, the Panel attempted to ensure that:
1. Goals and indicators for principles of Ecologically Sustainable Forest Management should be set
for the ‘whole of forest’ (spatial scale).
2. Consideration of ‘Sustainability’ should involve a time frame longer than that covered by a Forest
Management Plan (temporal scale). Some goals will not be achievable within that term but there
will be indicators that can be used to assess progress towards those goals.
3. Setting of goals and indicators should recognise the precautionary principle.
1.4
Outcomes of previous reviews
This review builds on the earlier Stage 1 and Stage 2 progress reports ( Ferguson et al., 2001a and b ) and
a review of maps and data (Ferguson, 2002), together with a number of other reviews carried out as part
of the Regional Forest Agreement (Turner,1998) and development of the Forest Management Plan.
Further reference to remaining issues will be made in the course of this review but suffice it to say for
now that a great deal of progress has been made in addressing the recommendations arising from previous
reviews.
The review also draws on comments received in public submissions on the Draft Forest Management Plan
(Conservation Commission, 2002b). The number of submissions received (circa 5,700) suggests that
forest issues continue to a high priority for many stakeholders.
1.5
Risk assessment and management
In considering application of the precautionary principle, the Panel paid particular attention to forest
management processes and practices dealing with ‘risk assessment’ and ‘risk management’ to minimise
environmental impacts and avoid serious or irreversible damage to the environment.
As noted in the Stage 1 report (Ferguson et al., 2001a) the guiding methodology for risk assessment and
management was based on the Standards Australia and Standards New Zealand publication AS/NZS
4360:1999 Risk Management. This provides a well-established and systematic approach that is
compatible with the Environmental Management System adopted in the Regional Forest Agreement
process, having been developed “with the objectives of providing a generic framework for identification,
analysis, assessment, treatment and monitoring of risk”.
Some of the key terms are defined as follows:
Hazard: a source of potential harm or a situation with a potential to cause a loss.
Likelihood: used as a quantitative description of probability and frequency.
Risk: the chance of something happening that will have an impact on objectives.
Residual risk: the remaining levels of risk after treatment measures have been taken.
3
2
FOREST AREAS AND MAPS
2.1
Introduction
The area of forest available for timber production is clearly a critical component for any calculation of
sustained yield. For the purposes of establishing this area, it is useful to distinguish between two
categories of land which are no longer available for timber production - new or proposed 'formal reserves'
and 'informal reserves'.
2.2
Formal reserves
The Government has determined that a number of areas are to be added to the formal reserves for
conservation or other purposes that specifically exclude timber production. In addition, the Conservation
Commission is recommending that certain other areas be placed in formal reserves because they have
high conservation value or are valued for other reasons by local communities (Map 1 attached). The
Government has not yet taken decisions on the latter. Although decisions have not yet been finalised on
all of these proposals, all of the reserves indicated on Map 1 have been taken as the basis for determining
the areas available for timber production under the proposal outlined in Appendix 15 of the Interim
Proposed Forest Management Plan (known as Scenario D) and referred to for the options examined in this
report.
2.3
Informal reserves
There are other informal reserves imbedded in the areas of forest outside the formal reserve system.
These include specified travel routes, river and stream buffers and patches of old-growth forest outside
formal reserves.
Informal reserves can generally be identified accurately on maps and taken into account in the
identification of the areas available for timber production. The matter of differences between prescribed
and field boundaries is taken up in a later section, but this issue is minor relative to the base area
involved. Informal reserves have been recognised in the scheduling carried out in developing the various
options in this report.
Scenario D of the Interim Proposed Forest Management Plan also includes a series of fauna habitat zones
which although not designated as informal reserves, they have been excluded from the area available for
timber production for period of the analysis.
The distribution of these reserves in shown for a part of the forest estate at a larger scale in Map 2
attached.
2.4
Stratification and maps
The area of forest available for timber production is mapped into various classes of vegetative cover using
aerial photography and field assessment. The intention is to separate out types that are reasonably uniform
in species, structure, silvicultural status and productivity class but different, one class from the other. The
labels given to the classes are descriptive of the principal species, structural and productivity classes and
this has given rise to some misunderstanding. The resultant mapping is not and cannot be perfectly
accurate in terms of species or structures or productivity class. While resolution is continually improving,
it is difficult to envisage that there will be the resources available to map attributes at increasingly fine
scales and there will therefore always be some uncertainty at the scale of metres and hectares.
It would matter little if the strata were given non-descriptive and arbitrary labels such as A, B and C.
They are a broad-scale planning device to improve the efficiency of the subsequent field sampling and to
facilitate prescription of silvicultural treatment appropriate to the type. Provided the later sampling is
objective, the mean estimates will reflect faithfully the average composition of the stratum in terms of
species, and hence the differences between strata.
Errors in the labelling of particular areas of strata may therefore occur due to the effects of fire or pest
attack on crown imagery or due to errors in historical records of previous harvests, or in the difficulties of
interpreting particular characteristics from aerial photos. It is important to recognise that many of the
categories are separated by ‘soft’ boundaries (for example some forest types) and that precise boundary
identification is neither possible nor sensible. Where errors are discovered in the course of field work,
changes are made to the official database under a well-established protocol and the dependent area data
4
are recalculated at the next revision of the database. The database is also revised prior to each run of the
sustained yield model. Thus each current set of estimates is based on the best available set of data at the
time.
The area of greatest sensitivity in the concerns expressed by the public is the incorrect labelling of some
‘old-growth’ patches of forest. This would mean that the area concerned is not shown as ‘old-growth’ and
might therefore be denied the protection which the policy introduced by the present Government seeks to
implement - namely to set aside from timber harvesting all areas of old-growth on land vested in the
Conservation Commission.
This issue highlights the distinction between planning at a strategic level, which is the basis of the
calculation of sustained yield, and operational planning and management on the ground. Operational
planning requires tree-markers to note and implement Government policy relating to such patches, so they
would be identified in the field regardless of the stratum label, and would be reserved from logging. There
is, however, a contingent issue relating to the area of forest available for timber production because the
patch of ‘old-growth’ forest missed in typing from photos now forms part of the productive area, whereas
it should not. But there are also patches typed as ‘old-growth’ that are not old-growth and that need
similarly to be corrected after due process from field checking. These errors tend to cancel and the issue is
what the net effect is and what allowance is made for the net effect on sustained yield, matters which are
taken up in a later section
The present stratification of the forest provides for a total of 263 strata defined by species, forest
structure, harvest and silvicultural history, incorporating 39 geographical areas (Supply Cells) across the
forest. They are confined to the net area of forest that is available for harvest. The stratification used for
this review of sustained yield has been revised from that used in previous analyses. The current
stratification places greater emphasis on geographical subdivision, recent silvicultural status and ensures
that each strata is large enough to contain a reasonable number of inventory plots to improve the precision
of estimate in each strata.
The pre-1980 regrowth karri forest has been re-stratified incorporating a new and improved estimation of
site productivity and of stocking. The two-tiered karri forest available for timber production was restratified as part of the new inventory.
The Panel has conducted simple random checks on the capacity of the geographic information system
(FMIS) to accurately reflect the areas of the various strata. Subject to the limitations imposed by the
minimum size of approx 0.5 ha pixel and the shape of cell that can be identified by the system, the Panel
is satisfied that the area estimation is accurate. (It is necessary to recognise that the source data for the
GIS system may have been captured at a greater or lesser resolution that 0.5 hectares, depending on the
attribute). The stratification is also sufficiently accurate and robust for calculating sustained yield and
later reference is made to relevant allowances for errors. These errors are quite small in aggregate net
effect. The risks associated with stratification and area estimation are very low, and the residual risks
even lower.
Conclusions
The Panel noted the substantial number of concerns expressed about the stratification and mapping. It
concludes that these reflect a widespread misconception of the basis and nature of the system. Corrections
or queries about strata from stakeholders are to be welcomed and will be checked and amended, if
appropriate. However, they have no significant effect on overall capacity of the system to properly and to
accurately calculate sustained yield.
5
3
INVENTORY
3.1
Jarrah
The underlying inventory of standing volume that supports the determination of yield is based on a
systematic sample of 12,248 photo plots that estimates species composition, stand density and height,
from which an estimate of gross bole volume is derived. A systematic subset of 1227 plots is measured on
the ground to provide detailed descriptions of each tree that can be used through a program known as
IRIS to estimate product volumes. The relationships between the two sets of plots provide for improved
sampling error.
The current jarrah inventory (photo and ground plots) was established in about 1990. Given that spatially
explicit adjustments have been made for areas that have been harvested or removed from the net area
available for this plan, the ten year old inventory represents a conservative approach but the Panel does
not consider that this represents a significant source of error in the determination of sustained yield.
Nevertheless, consideration will need to be given to the most appropriate form of inventory update for the
next revision of the plan.
Stratum volume for each of the 210 jarrah strata is derived from the plots that fall within each of the
strata. In estimating the yield that could be expected from these strata if they were harvested to different
prescriptions, individual ground plot data are imported into the simulator SILVIA and the results of
individual plot analysis is averaged, providing a more realistic simulation than that which would result
from assuming a average stand structure for each stratum.
The result of the ground plot analysis is then adjusted according to the relationship that exists between the
gross bole volume of the ground plots and the photo plots.
The final stage of the inventory is the adjustment that needs to be made to allow for the difference that
may exist between the estimated product volume and the product volume that actually exists (the
inventory bias), and the difference that exists between the actual product volume made available and the
volume that is recovered in harvesting (the utilisation factor). The combination may be additive or
compensatory. The level of the former is not necessarily important provided it is known and repeatable.
The level of the latter indicates both normal and expected operational loss in realisation and in some
cases, the potential for increased yield by improved recovery.
This stage of the inventory is based on the re-measurement of ground plots after the plot has been
harvested. Because relatively few plots are harvested each year, it requires some years to acquire a
sufficient sample on which to make reliable estimates. Sufficient data is now available to allow
comparisons to be made with a reasonable degree of confidence. The present estimate is based on an
analysis of 3319 trees from 123 plots harvested and remeasured since 1993. These data indicate that there
was an overall difference between the inventory estimates and the operational recovery of sawlogs of
minus 33%.(i.e. combined total of inventory bias and utilisation factor). This conversion factor is applied
to the inventory based estimate to give an estimate of final sawlog yield outputs which is then used in the
scheduling process. As noted above these data were derived during the period from 1993 to 2002 and
capture operational experience over that time period. It is considered to be a conservative estimate
considering the improvements to utilisation that are expected with a re-structured industry.
For future yields predicted from the growth model, downward adjustments of 30-70% have been made
according to tree size and age and the type of operation. These are also likely to be conservative in the
longer term as repeated thinnings improve the overall quality of the trees remaining, and technological
changes are expected to improve the utilisation of smaller logs.
However it is also apparent that a single adjustment figure is unlikely to be equally applicable to all strata
and tree size, nor will it continue to be appropriate with changing standards of utilisation.
Conclusions
The Panel considers that the design of the inventory system represents Australian best practice, and that
with the adjustments described above, provide inventory estimates at an appropriate level of precision and
confidence for strategic yield scheduling.
The Panel has been advised that the largest source of difference between the estimate and sawlog
acceptance is in trees that are made available for harvest but are left standing, rather than the full
utilisation of felled trees. This suggests that more attention is required to ensure that potentially suitable
sawlog trees (albeit marginal) are felled and utilised.
The Panel also recommends that during the life of the Plan, greater emphasis is placed on increasing the
6
sampling framework for monitoring, and to extend the analysis to separate inventory bias from the
utilisation factor. Given the expected changes to utilisation that will evolve with the re-structure of the
industry and the time required to accumulate sufficient sampling we do not consider that adjustment to
the yield is likely to be required before the next revision of the plan.
3.2
Karri
Since the Panel’s Stage 1 report, the two-tiered karri forest available for harvesting has been re-mapped
and stratified with up-to-date colour aerial photography into approximately 10 strata together with a
further 30 regrowth strata. More than fifty ground plots in patches of forest over 5 ha in size were
measured with full tree descriptions for analysis in IRIS, the system previously developed for the jarrah
inventory system. Small areas unavailable for harvesting for operational reasons have been excluded from
the net area, reducing the total volume estimated to be operationally available for harvesting.
Comparison of estimated volume and utilisable volume in mature karri forest under a clearfelling regime
has been relatively straightforward since most trees are felled and utilised for one product or the other,
and for areas where reliable comparisons were possible, sawlog removed were 34% less than estimated
availability. This adjustment has been applied to the new estimates. Future adjustment for utilisation of
sawlog from two-tiered forest will be done using utilisation monitoring plots established for the purpose.
Product volumes in regrowth stands are based on a ratio of the tree bole volume and are explicitly
specified in KARSIM. The ratio is varied principally on the basis of size, with specific allowance made
for defect such as butt damage due to Armillaria or excessive branching etc. An overall conversion factor
of - 30% has been applied to the modelled estimates of sawlog with higher allowance made for younger
stands and lower amounts for later operations.
Experience with the use of regrowth trees for a range of sawlog products that is envisaged under the restructured industry is limited. A monitoring system that provides feed back on the utilisation of sawlogs
from different sized regrowth trees with varying defect needs to be developed to inform the decision on
adjustments to expected yield. This is likely to be very dynamic over the life of the plan as the new
industry and new markets develop.
Conclusions
The Panel endorses the inventory system that is in place, and until more data is available, the Panel has no
basis for suggesting variation to the current allowances while recognising that they are likely to be
conservative.
3.3
Recommendation
Recommendation 1
In refining the inventory during the life of the Plan, greater emphasis should be placed by the
Department of Conservation and Land Management on increasing the sampling framework for
monitoring, and extending the analysis of monitoring data to separate inventory bias from the utilisation
factor, in addition to updating the field sampling.
7
4
GROWTH
4.1
Jarrah
In its Stage 1 report the Panel recommended that research and development of a new growth model that
reflected a wider array of silviculture and sites should be initiated during the next plan period.
Considerable progress has already been made in this respect with the development of the growth model
JARSIM.
Dieback-affected forest
The area of forest to which the dieback prescription is applied is initially based on known dieback
occurrence and the assumed impact associated with Vegetation Complexes. For future harvesting
different proportions of a stratum are assigned to a dieback prescription according to the proportion of the
strata expected to be impacted by dieback at the estimated rate of spread at different times in the future.
This varies the timing and nature of subsequent operations modelled by the FORSCHED scheduler
because different growth rate estimates or prescriptions are assigned to areas according to predictions of
dieback spread and impact.
Regrowth forest
For the purposes of calculating sustained yield, growth is allowed for on existing or future regrowth
stands based on estimates derived from JARSIM. JARSIM represents a forest stand as a list of trees
described in terms of species, diameter and bole height. The initial input lists of trees are based on
inventory of more than 1000 plots covering the range of sites available. These individual trees are
‘grown’ on the basis of algorithms in the model. The ‘grown-on’ tree list can be input into the simulation
model, SILVIA, where the appropriate silvicultural treatment is applied and resultant 'grown-on' tree list
provides the base for the next simulation period. Different growth rates are applied according to a range
of factors that include site, stand age, stocking, species mix, relative size of the ‘tree’, timing and intensity
of thinning. Where appropriate, the final outcomes from the results are derived as the mean output of a
range of plot conditions within a strata which is more realistic basis for estimate than assuming an
average ‘stand’.
Growth applied to regrowth stands is therefore derived from the growth model rather than by direct
application of growth from permanent sample plots (growth plots), although data from those plots as well
as from a range of thinning and inventory plots have been used in the development of the model. This
approach makes it possible to estimate growth, or rather future stand condition, without the need for
permanent growth plots that fully replicate those conditions . Total predicted growth is constrained to
ensure that realistic levels of stand density are not exceeded. This limit to density is derived for a range of
sites from an analysis of jarrah inventory plots. The model also provides for the influence on growth of
retained habitat trees. This enabled the change in prescription from 4 to 6 retained habitat trees per
hectare to be taken into account in a robust and appropriate manner.
Gross checks
To arrive at a level of confidence that might be placed on the growth estimates that have been used for the
calculation of sustained yield the Mean Annual Increment (MAI) of the total volume production predicted
from JARSIM over a 200 year ‘rotation ’was compared with the Periodic Annual Increment (PAI) of total
volume derived from 68 growth plots established across the jarrah forest at three levels of site quality.
While acknowledging that this comparison has limitations it is nevertheless the best that is available. The
MAI that was used for each of the site qualities in the regimes used in JARSIM varied from 55% to 85%
of the mean PAI of the growth plots in those site qualities. In the Panel’s view this level of conservatism
is appropriate until more data is available.
A further check on the influence of growth estimates on the level of sustained yield was made by running
a sensitivity analysis of varying growth rate. These were based on increasing both the variability of
growth and by considering an increase or decrease in mean annual growth by up to 50%. This indicated
that the impact on the yield of a regrowth stand over the whole rotation was somewhat less than the
percentage change in growth rate i.e. a change of ± 25% in growth rate might result in a ± 20% change in
volume yield. However because these regrowth stands will not make a significant contribution to sawlog
yield for many years, the impact on wood flow would not be felt for at least 50 years and have little
impact on the non-declining yield.
No growth is assumed on the existing two-tiered forest. The proportion of growth in the future standing
volume of these stands before the anticipated time of harvest varies from relatively small compared to
8
estimates of standing volume to quite substantial in the case of strata not scheduled for logging until 50
years hence. This represents a very conservative approach and merits checking during the period of the
Plan.
Conclusions
The Panel is therefore of the view that the growth estimates that have been used are appropriate for the
estimation of sustained yield in this plan.
The precision of the output from the JARSIM model can be improved over time in several ways:
•
As more data becomes available from younger stands over a greater range of sites as a basis for
initialising the model;
•
Improving the estimates of stand condition following thinning as a result of post thinning
monitoring;
•
Improving the understanding of forest dynamics by further research on the response to multiple
thinnings;
•
Reviewing the existing framework of growth plots and establishing new plots in stands that
more closely represent the structure of future stands.
Significant improvement in the available data cannot be achieved for at least a decade and there is little
value in further development of the growth model until that is available.
4.2
Karri
The approach used in the estimation of growth in the karri forest is similar to that in jarrah i.e. no growth
is assumed for two tiered stands, and regrowth stands are assumed to grow and develop according to a
growth model, KARSIM (Rayner, 1992).
KARSIM has been developed using data from a series of 214 even-aged plots across the range of sites in
the karri forest ranging in age from 2 to 135 years old. Future stand condition predicted by the model is
responsive to site quality, stocking, density, tree size and stand age.
Since the Panel’s Stage 1 report, considerable progress has been made in the base data used to initialise
the growth model. Almost all existing regrowth stands regenerated before about 1980 have been stratified
according to site quality and stand density using a combination of aerial photography and ground plots.
Different growth rates are applied on the basis of these strata. Younger regrowth will be stratified as they
reach an age when site quality is reliably expressed (about 20 years of age). Until that time stands are
estimated to fall into one of three site qualities.
Where full tree descriptors are available, future stand condition could be input to the simulation model,
SILVIA, which predicts a thinning yield and provides an estimate of the tree size distribution for input
back into KARSIM to be ‘grown on’. Post-thinning stand density sampling contributes to the validation
of these assumptions.
Conclusions
The Panel is of the view that growth and future stand condition has been estimated at a precision
appropriate for sustained yield calculation with the expectation that the precision of the model will
progressively improve as more data becomes available over time.
The predicted future stand condition and the expected condition following the simulated harvest are
recorded for each simulation run providing satisfactory transparency of the assumptions made.
4.3
Recommendation
Recommendation 2
In refining the growth models over the life of the Plan, the Department of Conservation and Land
Management should adopt a strategic approach and seek to obtain data from a broader range of ages
and conditions as those opportunities become available. Major refinement of the growth models is
therefore unlikely to be feasible until towards the end of the Plan period.
9
5
FOREST HEALTH
5.1
Introduction
In the Stage 1 report (Ferguson et al. 2001a) the Panel considered and made recommendations concerning
the possible impact of various pests and diseases, which have subsequently been pursued or are in train.
Of these, dieback was by far the most important.
5.2
Dieback disease
Dieback disease represents the most important hazard to future growth, the calculation of sustained yield,
and biodiversity for the jarrah forest. With regard to the dieback hazard, the Panel made two
recommendations :
(1) Recommendation 4.3 Dieback from Ferguson et al. (2001a). The key points of the
Environmental Protection Authority advice on the Protocol for the identification and
prioritisation for the management of Phytophthora cinnamomi “protectable areas”
endorsed by the Minister should be implemented as soon as possible. (EPA 2001
Bulletin 1010)
(2) The impact of future infection should be taken into account by sensitivity testing in the
simulation models, assuming variously (a) no spread and (b) the apparent past spread
over the last decade for the various strata.
Partly as a response to Recommendation 4.3 (2), detailed research has been carried out by the Department
of Conservation and Land Management staff (Strelein et al. in prep). They estimated rates of spread and
intensity of the impact on growth. Data on the rate of autonomous spread were collected from some 50
existing disease boundaries selected from about 260 initial sample sites. The selected sites were restricted
to those in which autonomous spread could be confidently and precisely identified over periods of 5 to 17
years. Records and ground truthing enabled mean annual rates of spread for 4 zones and for differing
slope conditions within them to be measured. Data were analysed and a predictive algorithm for FMIS
developed. These estimates have been used to model spread within impact classes throughout the Southwest forests.
New maps of current and projected distribution of dieback (see Figure 5.1) presented to the Panel
demonstrate the enormity of the problem and the hazard it presents to the critical values of the forest and
associated ecosystems in both production forest and reserves. The work done in relation to the assessment
of future impacts of the disease on sustained yield is a major advance with many important implications.
The work has resulted in a significant revision of the sustained yield calculations for the plan. The maps
produced illustrate the large area where P. cinnamomi has, and will continue to impact on biodiversity
and productivity.
Effects of dieback on sustained yield.
Allowances for the effects of dieback on yields have now been made based on projected future dieback
spread and impact. Different categories of forest have been defined on the current or predicted disease
status. The disease status changes according to the predictions of spread and impact over time and
spatially.
•
Infected or “unprotectable high impact” forest may be logged but a basal area of 15 m2/ha of
standing live trees (preferably resistant species) must be retained where possible. No future yield
is projected off such areas.
•
Infected areas where disease impact is moderate can be logged according to the standard jarrah
harvesting prescriptions but future yields are discounted by 60%.
•
For infected areas suffering only low impact, standard jarrah prescriptions may be applied with
no provision for reductions to future yield.
10
Figure 5.1 A map illustrating the simulated autonomous spread of dieback over time. The colours depict
the modelled extent of dieback infestation at successive 60-year intervals. White areas remain free of
autonomous dieback spread at 2181.
11
In the indicative simulation used for the sensitivity analysis, the projected extent of dieback in the jarrah
forest available for timber production under Scenario D (b) (Table 9.1) increased over time from 14% in
2001 to 34% by 2061 and 46% by 2121 and 54% by 2181. The illustrative projected spread of dieback
across vegetation complexes within the area of forest available for timber production used in the
woodflow scheduling for Scenario D (b) is indicated in Table 5.1.
Table 5.1 Dieback spread and impact.
Year
High impact vegetation
complexes
Area (ha)
% of net area
infested
scheduled for
harvesting *
2001
2061
2121
2181
48,300
86,700
108,200
120,700
6.2
11.2
13.9
15.5
Moderate impact vegetation
complexes
Area (ha)
% of net
infested
area
scheduled
for
harvesting
58,800
169,300
235,200
276,500
7.6
21.8
30.2
35.6
Other vegetation
complexes
Area (ha)
% of net
infested
area
scheduled
for
harvesting
13,500
39,800
59,200
73,900
1.7
5.1
7.6
9.5
* The net area scheduled under Scenario D was 777,534 ha
Recommendations of Environmental Protection Authority Bulletin 1010
Although interagency liaison on the implementation of the Bulletin 1010 still occurs, the Dieback
Consultative Council now takes on a lead role in coordinating the implementation of the
recommendations with Bulletin 1010 and developing a framework for the state-wide management of P.
cinnamomi. Considerable progress has been made in a number of areas and the Dieback Consultative
Council is progressing the scoping of an Environmental Protection Policy for the “Management of P.
cinnamomi and disease caused by it (Dieback) in native vegetation in Western Australia”. The Dieback
Consultative Council, after consultation with key industry stakeholders, has also provided the Minister
with advice on implementation of Recommendation 4 of the Western Australian Review Panel (Podger et
al. 1996) which stated: That industry, institutions and government agencies jointly address the extent to
which operational schedules can be modified to ensure that activity on the protectable areas is focussed
on minimising access during conditions which are conducive to dispersal of the pathogen and its
establishment. Many of the Dieback Consultative Council points of advice are relevant for the
management of both non-timber production areas of the Plan area as well as production areas.
In addition it should also be noted that the Department of Conservation and Land Management is
preparing an updated dieback policy for lands vested in the Conservation Commission.
In 2001 an expert working group was contracted to report to the Conservation Commission on the
feasibility of designing a trial of the “Protocol for the identification and prioritisation for management of
Phytopthora cinnamomi protectable areas as an experiment.” It concluded that it was not feasible to have
an experimental type trial to compare the previous hygiene system with that currently being used but the
need for information on past rates of spread in different ecosystems was recognised.
Conclusions
For the jarrah forest over the period of the Plan, dieback must be considered the greatest natural hazard to
biodiversity and a major risk to the health and vitality of a number of ecosystems
In view of the rapid progress by the Department of Conservation and Land Management in collating data
on rate of spread, the recommendations of the Conservation Commission based on those of the expert
working group may require updating or modification before they are forwarded to the Minister.
The maps of projected spread of P. cinnamomi will inform decision-making in a range of policy and
management areas with respect to future impacts of dieback, not only on wood flows, but also
biodiversity and ecosystem health and vitality. The methods developed have great potential in the
definition of “protectable areas” and the setting of priorities for management in a range of ecosystems,
regardless of tenure. The Panel identified a need for further commitments on dieback management, hence
the mapping of infections, within the conservation estate.
12
The new simulation and mapping system also has the potential to be a powerful tool in demonstrating the
effects of random infections on areas currently free of disease. This should be encouraged, as it is a useful
way of demonstrating the consequence of poor hygiene on future spread. Best practice with regard to
minimising dieback impacts is dependent on the use of this simulation and mapping system and its further
refinement over time.
An earlier recommendation of the Environmental Protection Authority was that results of past monitoring
of dieback spread and occurrence should be collated and made public. The Department of Conservation
and Land Management now have material in a form that can be distributed following finalisation.
The findings and predictions of the Department of Conservation and Land Management research project
should be used to assist in the implementation of a number of the recommendations stemming from
Environmental Protection Authority Bulletin 1010 and related reviews. While much has been done in
developing these for the management of the productive forest, they merit revision in the light of this new
information. In addition, the Panel is especially concerned that little appears to have been done in
developing management prescriptions specific to the conservation reserves concerned. In the light of this
recent research, this represents a significant risk to biodiversity.
5.3
Recommendation
Recommendation 3
Department of Conservation and Land Management resources should ensure that disease status of
‘uninfested’ areas in both production and conservation areas is monitored adequately and reported
separately for the production forest and reserves, with amendment of Key Performance Indicator 14 in
the Interim Proposed Forest Management Plan accordingly.
The results of research relating to the spread and impact on jarrah growth of dieback should be
(i) promulgated in an appropriate form to the Western Australian community by the Department of
Conservation and Land Management.
(ii) used to assist the implementation of Environmental Protection Authority and related
recommendations on the management of the productive forest and especially on the management of
conservation reserves.
The Department of Conservation and Land Management should ensure that the new dieback spread and
impact models are further developed, especially to model the effects of random or new infections in areas
of differing potential impact and that Objective 13 of the Interim Proposed Forest Management Plan be
amended accordingly to incorporate the action.
13
6
SELECTING AND APPLYING
SILVICULTURAL TREATMENTS
6.1
Introduction
Since the Panel’s Stage 1 report (Ferguson et al. 2001a), the Department of Conservation and Land
Management has developed and implemented a new computer-based silvicultural modelling system
(SILVIA) to help estimate the likely yields from forest harvested to any specified silvicultural
prescription and to quantify the variation arising from changes to silvicultural prescriptions. The
prescriptions in the model are specified in a manner that as far as possible captures the prescribed
Department of Conservation and Land Management Silvicultural Guidelines for the major species types
(jarrah, karri and wandoo). The development of SILVIA is a response to the statement in our report
“Yield estimates should be re-calculated whenever changes to silviculture are proposed so that changes to
the yield are included in the evaluation of the proposal” (Ferguson et al. 2001a; p 44).
SILVIA accesses plot data in which individual trees have been measured and classified. Attributes such
as species, size, sawlog presence, growth and silvicultural status, form, basal area, dominance and bole
condition are available for applying tree-marking rules to a stand. All trees are flagged for their candidate
status for tree marking (crop tree, habitat tree, potential crop tree, potential habitat tree, cull tree and/or
diversity tree) based on individual trees attributes.
The new Silvicultural Guidelines have been translated into a series of sets of rules representing the
treemarking rules for retention of basal area, habitat trees, crop trees, seed trees, and trees to be retained
for species diversity purposes. These rule-sets are applied to the stand (as represented by an individual
plot) to enable assessment of various silvicultural and management objectives (including the habitat tree
prescriptions) and application of silvicultural regimes (eg. shelterwood, gap creation, selection, thinning,
silvicultural treatment or clearing from mining).
SILVIA is then used to generate the expected yields associated with the harvesting of jarrah, karri and
wandoo stands based on the various specified silvicultural prescriptions. The trees in the residual stand
following the predicted harvesting are processed through the growth simulation packages to estimate
growth. Predicted plot volumes in SILVIA are aggregated for the stratum and then used for scheduling.
6.2
Achieving balance
The Stage 1 report (Ferguson et al., 2001a) recognised that a deficiency in the planning process was that
objectives were unclear or not evident, making it difficult to adequately evaluate balance or trade-off
between competing values and the appropriateness of the balance between competing objectives. Tradeoffs between values and objectives are important considerations as the Recommendations 3.4 Local
reservation and exclusion tradeoffs, 3.12 Structural goals, 4.1 Whole of forest and landscape targets, 4.2
Fire management, 4.8 Bauxite mining sites in the Stage 1 report illustrate.
Burrows et al. (2001, 2002) also commented on this deficiency. They raised a major shortcoming of the
present planning system being the lack of clearly articulated over-arching objectives to provide a
framework for development of plans and associated guidelines. The overall planning framework, goals
and objectives have to be understood as does the interrelationships between policies, agreements,
contracts, plans, guidelines, prescriptions and codes of practice. This is necessary background to the
consideration of trade-offs between wood and non-wood products. Further, Burrows et al. (2001,2002)
proposed a new conceptual and planning framework that could assist in the delivery of ecologically
sustainable forest management and achieving better integration of forest management.
Burrows et al. (2001) identify that clear objectives at various scales for forests are required to deliver
ecologically sustainable forest management. They propose a cascading set of objectives. Hence for
parcels of forests these cascading objectives should guide silvicultural decisions and management in
balancing trade-offs between wood and non-wood products.
Explicit objectives are required in the Plan to allow operational decision-making processes to occur that
will provide for transparent, repeatable and balanced decision-making for determining tradeoffs between
wood and non-wood values, particularly in terms of timber production, non-wood product industries,
biodiversity (habitat, fauna and flora values), recreation, water and aesthetics.
14
6.3
Fauna habitat objectives and structural goals
The Conservation and Land Management Act recognises the conservation of biodiversity (flora and
fauna) as a key objective. The biodiversity principle is factored into the calculation of sustained yield
through managing planning goals such as structural goals, netting down of area removed through
biodiversity prescriptions (Fauna Habitat Zones), applying reductions to yield to accommodate the
retention of habitat trees and conservation through the informal and formal reservation system.
The Interim Proposed Forest Management Plan has as its overall objectives for biological diversity: (i)
to conserve biodiversity accounting for principles of Ecologically Sustainable Forest Management; (ii)
the maintenance of self-sustaining populations of native species and communities and (iii) to ensure that
biodiversity recovers between one rotation and the next (whole of forest and landscape objectives). These
objectives are to be met through five sub-objectives using a sequence of strategies and actions.
A range of strategies and actions related to provision of fauna habitat (both spatially and temporally) in
production forest are to be undertaken. Together the reserve system, logged forest, fauna habitat zones
and habitat tree retention will contribute to the provision of overstorey and understorey vegetation
structure through time and contribute to structural diversity and to meet landscape and whole of forest
objectives. Fauna habitat zones are a mechanism to be put in place during the period of the plan to
contribute to the recolonisation of logged areas and to help prevent fauna species populations declining to
officially threatened status or declining to irretrievable low levels.
During the period of the Plan the following planning tasks are identified:
•
goals will be developed for understorey structural diversity at landscape and operational scales
that promote the maintenance of biodiversity (Action 6.A2)
•
guidelines for the protection of understorey species in silvicultural operations are to be
completed and incorporated into Silvicultural Guidelines (Action 6.A7)
•
guidelines for the selection and management of fauna habitat zones are to be completed and
incorporated into the Native Forest Timber Harvesting Planning Guidelines and the zones will be
identified and implemented (Actions 7.A1-3)
•
guidelines for the protection of selected habitat elements during timber harvesting are to be
completed and incorporated into Silvicultural Guidelines (Action 7.A12)
Burrows et al. (2001) recognised that while difficult, given the inherent complexity of biodiversity
through space and time and incomplete knowledge of biodiversity and disturbance ecology, the need for
having clear conservation objectives is of key importance. The clear specification of objectives assists in
setting silvicultural objectives and standards and making silvicultural decisions, determines sustained
yield and determines the acceptability of environmental impact.
Fauna habitat zones and understorey species protection initiatives in the Plan result from Burrows et al.
(2001, 2002). Their proposals were a response to a body of research arising from the consideration of
Ministerial Condition 11 and met the requirements of the Stage 1 Recommendation 3.4. Burrows et al.
(2002) specifically looked at the issue of habitat and biodiversity conservation with respect to jarrah
silviculture. Two issues were identified of fundamental importance to biodiversity conservation in jarrah
forests. The first issue was the “adequate provision of ‘legacy’ habitat components, such as large hollowbearing trees, hollow logs and patches of structurally mature forest”. The second issue was the
“development of whole-of-forest objectives for spatial heterogeneity of forest structures and age classes”
(Burrows et al. 2002: p. 11).
Clearly defined structural goals and objectives were identified as being important to the long-term
continuity of mature forest patches providing refugia for fauna within forests subjected to harvesting.
They identified that the adequate retention, distribution and ongoing availability of structurally mature
forest is important for the long-term protection and conservation of fauna depending upon these habitat
types. As a consequence they proposed a forest management unit scale conservation objective requiring
that a proportion of the unit retained mature or old-growth overstorey structural characteristics or was
within close proximity of forest with such characteristics.
Their report uses as an example of a reasonable measure to meet a forest patch conservation objective the
retention of a target 200 ha per forest block for the retention of mature or old-growth overstorey structural
characteristics (Burrows et al. 2002; option A). The basis for such a target is not documented. In their
discussion of the management of habitat for arboreal and hollow dependent species and findings from the
15
Kingston study they report that there is good evidence for retaining a portion of the forest block as uncut,
or with mature characteristics to provide refuges for faunal species requiring this type of habitat. The
retention of these patches is useful for recolonisation by some species of surrounding forest subjected to
disturbance. Using the Western Ringtail Possum as an indicator they proposed a minimum of 200 ha of
retained mature (or old-growth) patches in a matrix of regrowth forest; such patches were preferably
designed as continuous or connected (e.g. creek lines). Patches were to be developed through widening
stream reserves and buffers, and linking riparian areas and known habitat areas. Regrowth areas could be
inter-dispersed depending upon the dispersal capacity of threatened or vulnerable fauna species.
An alternative approach proposed by Burrows et al. ,2002; (option B) was to provide for a wider dispersal
of mature forest characteristics by retaining mature trees at a density of about 10-15% crown cover in all
forest that is more than 5 km from a reserve and where informal reserves constituted less than 20% of the
forest block. Burrows et al. (2002) recognised that the retention of mature forests as refuges would have
implications to wood supply. Bradshaw (2002) discusses the likely impact with respect to structural goals
of the Burrows et al. (2002) proposals.
The requirement for Fauna Habitat Zones was supported following workshops held in February 2003.
Support was based on the Kingston study highlighting the complexity between species sensitive to
logging because of their association with forest habitats that display “mature characteristics” in the
overstorey and understorey. Zones were seen as mitigating the risk that lack of full knowledge provides
given the workshops general assessment that the level of knowledge of fauna was poor with the
knowledge of invertebrates being less than that for vertebrates. The principle of zone selection should be
flexible and there was general agreement that zones should be spread across the landscape sampling a
broad range of habitats for a range of taxa and that habitat patches should not be restricted to mature
overstorey. Views were expressed that the critical issues were for arboreal species in eastern forest and
aquatic fauna in the western forest, while the southern forest was well represented by reserves.
Appendix 4 of the Interim Proposed Forest Management Plan provides the operational principles for
incorporating fauna habitat zones into the Plan up until the guidelines for the selection and management
of fauna habitat zones are developed and implemented. Zones are to be greater or equal to 200ha and
located no more than 3 kilometres from conservation reserves, large informal reserves or other fauna
habitat zones using specified decision rules. While zones can be rotated into regenerating forest over time
zones are not to be logged. As a result the impact on the area statement in the rotation period would
remain the same. Fire prescription to be applied is unclear and the possible increase in risk of fire as a
result has not been incorporated into the assumptions.
The Panel accepts the objective that management should ensure that biodiversity recovers between one
rotation and the next at the landscape scale and that an appropriate representation of mature habitat
elements will be required across the landscape to achieve this. Difficulty in planning and management of
these Zones will result from the absence of clear objectives or targets, the wide range of views on the
purpose of the Zones and rationale for excluding logging, the wide range of proposed selection criteria in
determining Zones and an absence of any evaluation of an appropriate landscape unit on which to base
these habitat elements. The Panel is of the view that these Zones should not be implemented until a more
thorough justification and evaluation has been undertaken from the commencement of the Plan.
In providing for the risk to sustained yield that any increase in Fauna Habitat Zones may involve an
allowance for retained habitat patches at the minimum rate of 200 ha per forest block, including existing
mature habitat in informal reserves was made for our assessment of sustained yield (see option 1, Chapter
9).
Structural goals are an important element of the current Forest Management Plan. The goal is based upon
a “natural’ distribution of forest structures that accommodate ecological principles and maintain a suite of
structural values across the forest estate. These goals are seen as important means to manage biodiversity
over a rotation period; an important consideration in the management planning process. They are also
useful in balancing and planning structural attributes between those found in the reserve system and those
in production forests. Fauna habitat zones, habitat tree prescriptions and the reserve system contribute to
the structural goals. It is important to incorporate structural goals at a whole-of-forest and landscape level
(Burrows et al. 2002). Goals should be described in the new management plan (see Stage 1
Recommendation 3.12)
16
6.4
Silvicultural prescriptions
Jarrah
The Draft Jarrah Silvicultural Guideline 1/02 (August 2002) builds on the Burrows (2001, 2002) reports
and, with the exception of some matters relating to trade-offs, incorporates conservation objectives into
the plan.
It is evident from Appendix 5 of the Interim Proposed Forest Management Plan that the advice of the
Burrows Panel has been accepted and many modifications to the jarrah guideline made. Effort has been
made to reduce the impact of silvicultural operations on flora diversity and abundance with a range of
measures relating to post harvest operations. Habitat requirements have been explored in a number of
ways with a number of specific changes incorporated into the current guidelines.
Salinity
With regard to measures to ensure that the levels of tree removal do not result in increased salinity in
streams emanating in the intermediate rainfall zone the conclusion of the Burrows Panel is endorsed by
the Panel. They found “no basis by way of new evidence for changing” the measures that have been
current during the last decade but noted that new data may become available from a major current
catchment study under-way in the northern jarrah forest. This is an important area of research and as
funds permit the program should be expanded incorporate monitoring of aquatic biota for reasons
outlined in Burrows et al. (2002) Panel report.
Water quality
An objective of the plan is to sustain water quality for biodiversity and consumptive uses. The Panel is
aware that there has been considerable discussion during plan development based on a report from the
Waters and Rivers Commission (2001). The outcome for the plan was that the current system of informal
reserves on streams was to be maintained but reviewed as outlined in the Interim Proposed Forest
Management Plan as part of adaptive management. A number of guidelines for the management and
maintenance of the stream-zone informal reserves, will also be reviewed during the first half of the plan.
A program for any change will be reported in the mid-term review of the Plan. The Panel was satisfied
with this approach and considered that this flexibility did not present a risk to sustained yield based on
the current allowances. Major increases of stream zone informal reserves are not envisaged.
Regeneration
Many modifications to the guidelines have been made to ensure jarrah is regenerated to satisfactory
standards across a range of sites and zones. Planned actions to address all the specific recommendations
with regard to regeneration, made in both the 2001 and 2002 reports by the Burrows committee have been
tabulated in an internal report prepared by Department of Conservation and Land Management and have
been incorporated into the strategies within the Plan.
Concerns about the regeneration adequacy of ‘eastern forest’ have been addressed in the Silvicultural
Guidelines by re-evaluating the acceptable stocking standards and shifting the emphasis to the
management of coppice regeneration, a more reliable form of regeneration in this environment. In
addition a field survey of regeneration in the eastern zone forest has commenced recently. The strategy is
to survey a number of attributes from a representative sample of eastern jarrah forest recently harvested
and treated to the shelterwood objective. The objectives of the survey are five fold and will generate
useful information on both form and stocking and levels of various stages of regeneration. One of the
objectives of the survey is to determine the effects of timber harvesting, overstorey competition, soil
disturbance and fire intensity on establishment of new regeneration.
Initial analysis of data from a very limited number of sites indicates considerable variation in results but
does not raise any concerns with regard to the maintenance of ecologically sustainable forest management
key values in the zone.
This data will inform future decisions on the management of eastern forest, but the Panel is of the view
that there is a low risk that any further changes will be required to the jarrah guidelines for the
management of the eastern zone jarrah that would impact on sustained yield in the long term.
Research
A commitment to the forest-monitoring program FORESTCHECK has also been made after the review of
the program initiated by the Burrows committee. Views of scientists external to the Department of
Conservation and Land Management were sought during the review and first results of the monitoring
17
have now been collated. Burrows et al. 2002 also summarised high priority forest research needed to
underpin ecologically sustainable forest management in the jarrah forest. Existing research programmes
already cover a number of the topics.
The Panel concluded that there has been a thorough review of the jarrah guidelines giving appropriate
attention to regeneration adequacy, the maintenance of flora diversity and fauna habitat.
Karri
Key changes to the karri guidelines are listed in the Interim Proposed Forest Management Plan Appendix
5. As many issues relating to the management of karri regrowth were considered in 1999 by the
Ministerial Advisory Group (Ferguson et al. 1999), further independent review of the karri guidelines has
not been necessary. Recommendations from the Ministerial Advisory Group have been incorporated into
the karri guidelines. Limitations to the size of clear fell patches are applied. They are 20 hectares for
regrowth forest and 40 hectares for two-tiered forest.
There are changes to the Silvicultural Guidelines, which relate to the greater importance of the remaining
two tiered forest contributing to the schedules and the recent dramatic increase in mature karri forest
being reserved. The requirement for the retention of patches of mature forest every 400m became
unnecessary following significant increases in the areas of formal and informal reserves and the
implementation of the Fauna Habitat Zones.
Marri retention
Loss of markets for large marri have led to recent consideration as to how best to manage both jarrah and
karri forest with a high proportion of marri. Excessive felling to waste is costly and aesthetically
unappealing. Retention of marri can inhibit regeneration of both karri and jarrah and eventually impact on
sustained yield. The guidelines have been revised such that if markets for certain sizes of marri are
unavailable removals will be concentrated in areas where marri stocking is low. During the plan period
current indications are that there may be markets for smaller rather than larger logs. Retained marri will
contribute to habitat in areas of two tiered forest currently scheduled for logging.
Trade-offs
The Panel is in agreement with Burrows et al. (2002) that the silvicultural system has to be viewed within
a broader ecological base to deliver ecologically sustainable forest management. Silvicultural guidelines
need to be able to cater for non-wood values to enable appropriate silvicultural decisions to be made.
Silvicultural decisions and practices can greatly change the forest structural and floral composition
spatially and through time resulting in differential supply of ecosystem services and products (including
water and biodiversity) through time. It is important that the Plan contain broader forest ecosystem
objectives and guidelines that inform silvicultural decisions. Ecologically sustainable forest management
is fundamentally about protecting the ecological integrity (biodiversity, health and productivity) of forest
ecosystems while sustaining a supply of products and services to the community (Burrows et al. 2002).
The Panel believes that the current interim proposed plan still lacks (see Stage 1 Recommendation 4.1)
clear objectives that enable trade-off decisions to be made in the context of forests at a whole-of-forest,
landscape, forest patch (block) and coupe scales. Such objectives are required for looking at
consequential impacts on wood and non-wood values and the potential effects on sustained yield. Hence
the Panel recommends that the Conservation Commission provide explicit whole-of-forest and landscape
objectives and targets that address these trade-offs during the period of the plan.
Fauna habitat zones and structural goals
The Plan needs to clearly articulate the objectives, role and purpose of Fauna Habitat Zones, as they are
currently unclear in the Interim Proposed Plan. The Panel understands that the purpose of the zones is to
assist species to recolonise adjacent regrowth forest as well as maintaining throughout the forest fauna
that depend on forest habitat characteristics that may be adversely affected by forest operations. Hence
Zones have a complementary purpose to forest set aside in formal and informal reserves.
These Zones may be placed on longer rotations or subjected to conservative logging with the objective of
managing primarily for faunal habitat characteristics while allowing the removal of sawlog as a secondary
objective. With appropriate training of Conservation and Land Management and Forests Products
Commission staff and clear specification of objectives these forests could be managed for both fauna
habitat and/or understorey flora and sawlog, so fulfilling Objective 7 of the Interim Proposed Plan.
The long-term objectives for sustained yield are determined by the objectives set through structural goals.
18
This issue is further discussed in Chapter 10. Structural goals determine the pattern of timber harvesting
over the period of the plan. These goals need to be enunciated in the Plan.
Silvicultural prescriptions
The Panel concluded that there has been a thorough review of the jarrah guidelines giving appropriate
attention to regeneration adequacy, the maintenance of flora diversity and fauna habitat.
With regard to measures to ensure that the levels of tree removal do not result in increased salinity in
streams emanating in the intermediate rainfall zone the conclusion of the Burrows Panel is endorsed by
the Panel. Burrows et al. (2002) found “no basis by way of new evidence for changing” the measures that
have been current during the last decade but noted that new data may become available from a major
current catchment study under-way in the northern jarrah forest. The residual risk to sustained yield is low
of further changes being required to the jarrah Silvicultural Guidelines for the management of the eastern
zone jarrah, which may impact on sustained yield in the long term.
Similarly the Silvicultural Guidelines for karri are well developed and the residual risk to sustained yield
of further changes is low.
The risk to sustained yield through marri being retained due to a future lack of markets has been directly
incorporated into the woodflow scheduling.
Conclusions
The Panel notes that the predicted verses actual outcomes of silvicultural treatments will be closely
monitored for the period of the plan and recorded in the silvicultural information system, SILREC.
Consistent differences between the estimated and actual estimates would have long term consequences to
the projection of sustained yield and hence future adjustments may be required resulting from such
monitoring.
The Panel is of the view that the proposed Fauna Habitat Zones should not be implemented until a more
thorough justification and evaluation has been undertaken.
6.5
Recommendation
Recommendation 4
The Conservation Commission should
(a) provide explicit whole-of-forest and landscape objectives and targets to help address the
trade-offs between wood and non-wood values at the various planning scales.
(b) clearly articulate the objectives and targets of Fauna Habitat Zones in the Forest
Management Plan.
(c) review the selection criteria for the Fauna Habitat Zones in the light of the above.
19
7
PROVIDING FOR RISKS
Introduction
A wide range of future natural and human induced events and broader environmental, economic or social
changes will have an impact on the forest and its ability to yield forest products and services in the long
term. Some of these will, or have potential to cause large impacts or change, some leading to reductions
in the yields of timber (or other products).
A range of factors have been evaluated as risks to the estimation or realisation of timber yields in relation
to the Interim Proposed Forest Management Plan by the Department of Conservation and Land
Management. Information was presented to the Panel by the Department of Conservation and Land
Management staff covering evaluation and where relevant, adjustment methodologies and quantities for:
1. Fire
2. Fungal disease (Armillaria, P. cinnamomi)
3. Insect attack
4. Immediate climate (frost, drought and waterlogging)
5. Longer term climate change
6. Salinity
7. Forest area loss and conversion
8. Management practice and implementation
9. Data uncertainty
7.1
Fire
The Department of Conservation and Land Management was previously requested by the Panel to
investigate the potential impacts of fire on the young even-aged karri resource (Ferguson et al., 2001a).
Fire losses for other forest types (jarrah and older karri) are considered (a) to be captured by the routine
inventory procedures, and (b) volume loss is limited because salvage log recovery is feasible, if needed.
Information presented by the Department of Conservation and Land Management suggested that stands
are at risk of complete timber loss (no recovery) between the ages of 10 and 30 years. After this age, log
material was assumed to be recovered. An analysis of fire probability and magnitude was undertaken by
CALM Science and Forest Management Branch of the Department of Conservation and Land
Management to fulfil this request. Analysis of previous records indicated an average loss of 1.7% over the
last 12 years. Simulations of wildfire spread from single events under relevant 95 percentile weather
conditions indicated average fire sizes of approximately 640 ha in karri regrowth.
The Karri Silvicultural Guidelines provide guidance for the silvicultural response to wildfire damage for
stands of different age and condition.
An area loss factor of 3.4% of young even-aged karri regrowth for the period of stand growth between the
ages of 10 and 30 years was used in the sustained yield calculations.
The Panel supports the approach and the fire risk setting for karri regrowth.
7.2
Disease
Reference has already been made to the prediction of dieback spread and impact. The impacts of these
predicted spread patterns on sustained yield were then assessed by running the FORSCHED system with
the revised dieback data.
The Panel supports the approach employed. A valuable new analytical tool has been developed. While
further research is recommended to better establish rates of spread of dieback, and to enhance predictive
modelling, the work already undertaken provides a valuable insight into likely impacts.
Armillaria is a significant naturally occurring fungal disease in Western Australian karri forest. The risk
of Armillaria induced mortality in regrowth forests increases with every operation that leaves stumps and
roots in place. The incidence of karri mortality post-thinning will be monitored. Impacts are assumed to
already be present in the inventory and growth plot data and allowance is made for the realisable yield
predictions. At the management level, a small group of specific “high risk” stands have been identified
and deliberately deferred from thinning to allow the results of monitoring to be assessed.
The Panel supports the approach.
20
7.3
Insects
Insect attack from Phoracantha acanthocera (bullseye borer), Uraba lugens (Skeletoniser) and Perthida
glyphopa (Jarrah Leaf Miner) are of importance. Allowance for bullseye borer is incorporated through
the identification of infected area and a modified allocation of log products from that area. No increase in
extent is assumed for the purpose of this plan. Incidence of Jarrah Leaf Miner is assumed to continue at
low background levels already incorporated in growth and inventory data. No escalation of attack is
assumed in the Plan but monitoring of the disease will need to be continued.
The Panel supports the approach adopted.
7.4
Immediate climate
Forest growth is affected by immediate climate i.e. frost, drought and, in some areas by waterlogging.
Past impacts from these sources are assumed to be already captured in inventory and growth plot data. It
is assumed that these factors will maintain the same level of effect for the period of the Plan. Potential
impacts of long term climate change are discussed below in Section 7.8. The Panel supports the approach
adopted.
7.5
Salinity
Information provided by the Department of Conservation and Land Management is that stands whose
management might contribute to increased salinity in catchments are actively managed to special
prescriptions. The Interim Proposed Forest Management Plan includes objectives and performance targets
covering monitoring of in-stream salinity levels for a number of catchments.
The silvicultural practice requires retention of a higher forest density than standard and in some areas,
increased in stream zones. This modified silviculture will result in reduced yield and the buffer extension
results in lost production area.
This effect is automatically captured in FORSCHED by the assignment of relevant areas to modified
yield regimes, and adjustment to the net available area data.
The Panel supports the approach taken.
7.6
Silvicultural practice
The sustained yield projected by the Department of Conservation and Land Management wood-flow
modelling systems assumes that silvicultural practice will be implemented according to the specified
schedule. Failure to implement expected silviculture arises in two main areas.
Variation from prescription
Variation from prescription in near-term harvesting cycles (i.e. failure to remove stems that should have
been harvested according to the guidelines) might result in different immediate yield and potentially
reduced long term growth. This risk is addressed in the yield estimation procedure through (a) reliance on
recovery and utilisation rates derived from field experience, and (b) growth projected from the long term
inventory data which should capture past actual performance. The future risk is addressed under
Department of Conservation and Land Management/Forest Products Commission procedures though
harvest planning and monitoring and is intended to be overseen by audit. The Panel believes the residual
risk is small.
Failure to implement scheduled follow-up silviculture.
In developing all options, the Department of Conservation and Land Management has stressed the
importance of thinning and especially the potential effects on sawlog yield that delay in thinning of jarrah
regrowth would have.
The Panel has no reservations about the importance of timely thinning in karri because this produces a
viable commercial return and is already in progress. Delays to this work do represent a moderate risk to
the karri sustained yield but possible delays to first thinnings in the regrowth karri have already been
factored into the yield regimes across site qualities. The projected sawlog woodflows therefore already
accommodate part of this risk. As well, the self-thinning nature of karri mitigates against major impacts
arising from delays in subsequent thinnings.
However, non-commercial thinning of jarrah regrowth at about 20 and 50 years is not considered
economically viable from the viewpoint of return on investment from wood products alone. Under such
21
an analysis incurring a cost of about $150/ha for each of the non-commercial thinnings represents a
significant investment that cannot be adequately recouped from later commercial thinning revenues, nor
from the sale of the final crop at any realistic stumpage price. This means that these early thinnings will
only be economically viable if there is substantial revenue from firewood, woodchips or similar
utilisation, or if significant economic value can be imputed to them from the additional water yields
generated. This may be true of some areas but is unlikely to prevail for most areas in the period of the
Plan and will hinge on utilisation of residual wood or the willingness of the water authorities and
Government to fund the thinning in the interests of water production.
7.7
Loss of productive forest area
There are ongoing losses of productive forest area to meet requirements of forest management such as
internal roads, water points and gravel pits, landings etc. Potential yield is also lost through inability to
access for harvesting for reasons of slope, temporary exclusion or discovered as being operationally
infeasible during harvest plan preparation.
The historical pattern of area losses for this group of uses has been analysed by the Department of
Conservation and Land Management. The analysis excludes mining because the past and future extent of
mining is separately identified in the scheduling. Data indicate losses ranging from about 4.5% for jarrah
to almost 10% for karri. The anticipated yield loss is allowed for by making a corresponding reduction in
net productive area in the yield scheduling system.
The Panel concludes that the level established and method used to make allowance for the risk is
reasonable.
There are also ongoing risks to sustainable yield through management initiated rezoning directly
removing forest from the harvestable area or through changes to operational or planning guidelines that
prevent harvesting access. Such actions automatically affect sustained yield. The Panel reviewed the
outcomes of the recent review of the adequacy of streamside reserves and buffers (Waters and Rivers
Commission 2001) with a view to establishing if there was a likely substantial impact on either the area
available for harvesting, including any changes associated with dieback, or rates of growth, or other
possible influences on the calculation of sustained yield. On balance, the Panel is of the view that the
implementation of the outcomes of that review will have marginal influence on the calculation of
sustained yield.
A number of adaptive management trials are proposed under the Plan and a number of Guidelines and
planning procedural documents remain to be completed. Changes to effective harvestable area, intended
to improve ecologically sustainable forest management are possible from any of these sources. The Plan
outlines a procedure for amending the Plan leading to approval by the Minister. Impacts on sustained
yield should be calculated whenever proposals involving significant alterations to accessible harvesting
area are proposed.
7.8
Long term climate change
Possible impacts of climate change were identified in the Stage 1 report of the Panel (Ferguson et al.,
2001). The Department of Conservation and Land Management have subsequently undertaken further
investigation and made some exploratory simulations of possible impacts.
Reviews of the literature suggest that climate change could lead to a reduction in rainfall for South-west
of Western Australia although the onset of such phenomena would be progressive over long periods.
Reduction in rainfall is associated with reduced forest growth. Simulations were performed under
scenarios of reduced growth and confirmed expected losses in sawlog and total log volumes. These would
principally impact on yield in the second century. Nearer-term yield depends on current standing
inventory and growth under current climatic conditions but long-term climatic changes would only affect
regrowth forest because no future net increment was assumed for most cohorts in two-tiered jarrah and
karri strata. There are other potential risks such as changes in disease patterns and possible increases in
occurrence of periods of extreme fire weather and in climatic variability (eg. droughts).
The Panel concludes that while the issue is an important one adjustment for climate effects is not
necessary in the current planning period. Actual forest growth should continue to be monitored as the
basis for forest yield simulation and possible adjustment for what is anticipated to be slowly changing
phenomena, to be considered at the time of the next plan (2014). A watching brief should be maintained
on relevant areas of climate change science.
22
Conclusions
The Panel has reviewed the methods used and the level of allowances made for the listed range of
hazards. The Department of Conservation and Land Management has evaluated prior experience in
relation to losses associated with these risks and the allowances made and the methods used to make the
adjustments are reasonable.
For several of the risk classes identified, the Panel has specific recommendations that should help in
reducing future additional losses. Area Reduction: The Panel recommends that any proposals for
significant changes in zoning or operational guidelines that affect harvestable areas must be accompanied
by a re-estimation of sustained yield to allow evaluation of impacts on ESFM values.
Phoracantha: During the period of the Plan, on-going monitoring should be conducted across the
thinnable karri regrowth estate to further assess the potential impact on yield and refine the allowance for
yield reduction to be used in the future.
Climate Change: Actual forest growth should continue to be monitored as the basis for forest yield
simulation and possible adjustment for what is anticipated to be a slowly-changing phenomena. Data
should be considered at the time of the next plan (2014). A watching brief should be maintained on
relevant areas of climate change science.
7.9
Recommendation
Recommendation 5
Further refinement of the expected scheduling of jarrah regrowth thinning should be undertaken during
the period of the Plan by the Department of Conservation and Land Management.
Any proposals for significant changes in zoning or operational guidelines that affect harvestable areas
must be accompanied by a re-estimation of sustained yield by the Department of Conservation and Land
Management to allow evaluation of impacts on ecologically sustainable forest management values.
23
8
SCHEDULING AND MANAGEMENT OF
LOGGING
8.1
Yield forecasting
The woodflow scheduling model (FORSCHED) operates by simulating the yield that would flow over
time if a particular harvesting and silvicultural regime (sequence of operations) is applied to a particular
area of forest. The present stratification defines 263 strata according to species, site quality, forest
structure, harvest and silvicultural history, incorporating 39 geographical areas (Supply Cells) across the
forest. They are confined to the net area of forest that is available for harvest.
The type of harvest operation applied to each stratum, its timing and intensity can be varied to achieve a
range of wood flow outcomes. In practice a range of ‘standard’ regimes, based on the Silvicultural
Guidelines appropriate to the particular stand structure, condition, location and dieback status are applied
and the timing of these operations is then adjusted to ‘smooth’ the yield as far as is possible within
various constraints (particularly silvicultural requirements) and arrive at the level of non-declining yield.
In general terms there are a number of harvesting operations that may be delayed to smooth the yield but
there are fewer opportunities to bring the yield forward.
The basic regimes that are applied may be generalised as follows:
•
•
•
•
A proportion of all strata within areas potentially available for bauxite mining are ‘cleared’ each year
based on predicted mining rates (historical). These areas are assumed to be regenerated as even-aged
stands and each of these stands then becomes a new ‘stand’ that is ‘thinned’ at appropriate times into
the future, before final felling at rotation age. The growth rate that is assumed for these regenerating
areas is currently based on the site quality of the stand as it was before mining. The intensity of
thinning is that specified in the Silvicultural Guidelines.
Strata that have been recently harvested to ‘shelterwood’ are scheduled for re-harvesting to a ‘gap’ at
between 20 and 40 years after the shelterwood cut (to allow for regeneration establishment). These
areas then become a new strata defined as regenerated, are ‘grown on’ according to their appropriate
site quality, and are ‘thinned’ at regular intervals in the future to the standards specified in the
Silvicultural Guidelines before gap creation with retained habitat is repeated at the end of the
rotation, at which time they are ‘regenerated’ and the process repeated.
The proportion of the jarrah two-tiered strata assumed to be thinned, harvested to a gap, shelterwood,
selectively harvested or harvested to an ‘eastern prescription’ is estimated. The ratio is informed by
past proportions, locality and the data derived from sample plots within the strata and by analysis in
SILVIA. The proportion of the strata that will be harvested each year is determined by the initial
period over which the strata is assigned to be harvested - initially based on the time from which
significant volumes of sawlog will be available from regrowth forest. The date at which this initial
harvest occurs fixes the periods for subsequent operations such as thinning, the second shelterwood
cut or the return to Temporary Exclusion Areas.
Existing even-aged stands are assigned to be thinned at a specified time to the density specified in the
Silvicultural Guidelines. The initial harvest date sets in train the dates at which future thinnings vary
according to site quality (i.e. growth rate).
Mention has already been made (Chapter 7) of the potential importance of thinning on the scheduling of
logging and thus on sustained yield.
The nature, the timing and the yield from each stratum is explicitly recorded for each analysis. While
relationships are complex, the basic operations applied to each strata are conceptually straightforward and
the recorded assumptions are transparent. It is nevertheless essential that any yield scenario that is
presented be accompanied by a summary of the key scheduling assumptions as well as those relating to
the area base.
During the review the Panel had the opportunity to examine a number of strata and were able to track
their development from underlying map data to their point of input to FORSCHED.
Although the new stratification includes spatial representation down to a silvicultural stratum within a
Supply Cell, it is not of a sufficient resolution for detailed operational planning involving spatial
adjacency issues. The schedules used in FORSCHED are therefore not fully spatial because they assume
that operations are applied to a proportion of a stratum within a Supply Cell, and not to a spatially
identified area within it. Hence the broad operational feasibility of these schedules is tested by simulating
24
logging operations over the Plan period in greater detail using a special and separate simulation program
(IOPS).
8.2
Log yields
Concerns have been expressed that the estimation of log grade yields are inaccurate and that there will be
substantial but unpredicted changes in the relative yields of different types of log from the forests to be
cut in the planning period. The Panel notes that three forms of describing and controlling log yield are in
use, (i) log grades, (ii) log description to diameter limit and (iii) whole bole volumes (being considered).
The details underpinning the system developed to predict log availability by grade and the procedures
used to establish interrelationship between these measures have been investigated by the Panel.
Estimates of log yield by grade are made in two steps. In the first, the extensive systematic forest
inventory database is interrogated for relevant plots located in the selected forest type and region. The
IRIS system is used to process the individual tree data and log crosscutting rules to provide estimates of
log availability to specified top diameters and defect limits. These are passed to the silvicultural analysis
tool SILVIA which can estimate yield under defined silvicultural prescriptions. Sawlog volumes available
by applying a 200mm Small End Diameter (SED) and a 300mm SED limit have been separately
estimated . In a second step, a set of conversion factors is used to estimate the operationally realisable
yield by grade. The conversion factors were established by the Department of Conservation and Land
Management using measured field plots, from logging records and some expert judgement. These have
been corroborated with longer term yield data. It must be emphasised that the system operates at the
forest stratum and not individual coupe level.
The Panel has investigated the operation of the systems and reviewed the derivation of the conversion
factors. It is satisfied that the system produces adequate estimates of utilisable yield for the planning
period. However, there are some residual risks. If technologies and practices change or there are
substantial changes in the acceptable grade descriptions, new conversion ratios would clearly be needed.
The Panel notes that from the viewpoint of yield estimation and control there are advantages to bole
measures. We recommend that consideration be given to changing to a bole sawlog (i.e. to nominated top
diameters) as a basis for yield estimation and control.
The Panel notes that there are many factors involved in ensuring that all economically recoverable yield is
harvested from logging coupes. Waste at the coupe level could lead to pressure to extend harvesting areas
to meet volume commitments, reducing long-term sustainable yield or conversely better utilisation would
reduce the area to be harvested for the same volume. Forest Products Commission staff and the harvesting
operatives play a key role. Ongoing development of the procedures and processes used to monitor
utilisation and the effective conversion level is needed by the Department of Conservation and Land
Management and the Forest Products Commission to ensure waste is minimised and planning predictions
are accurate. Comparison with pre-harvest forecasts of available volumes for an individual coupe can
provide only a guide because these are generated from stratum wide data and cannot reflect the specific
circumstances of each coupe. Estimates of conversion factors were necessarily derived from past and
recent operations. Periodic data needs to be collected across the range of coupes at the annual or three
year level. These should be monitored by the Department and Commission as a basis for improved
management and review.
8.3
Changes to log description
No scheduling will be workable if it is not viable for the industry purchasing the timber. Different species,
log sizes and grades may have very different logging and processing requirements and economic
implications. It is not possible for any planning model to reflect every variation but the current model is
sufficiently robust in its capacity to be able to predict the outcomes of most of the major differences.
The planning model can separate the yields of jarrah and karri sawlogs in two sizes, to a 300 mm top
diameter, and the additional volume above to a 200 mm top diameter. (The model is flexible and permits
processing to be performed to any top diameter limit or product description.) As noted earlier, trials to test
actual realised volumes against those estimated by the model indicate that they are sufficiently robust and
accurate for the purposes of planning yield regulation and the three-year rolling logging plan.
Whole bole volume can also be estimated so that the additional volume beyond that of the volume to
200mm top diameter provides an estimate of the residual wood that might be commercially acceptable for
uses other than sawing from the tops of trees felled for sawlogs.
There are proposals to change the basis of timber sale to whole bole measures. The Panel notes proposed
25
action 11.A6 in the Interim Proposed Forest Management Plan and recommends that additional work (if
necessary) be undertaken to ensure both grade and whole bole measures are accurately predicted by the
IRIS and SILVIA processing systems. The plot process currently employed by the Department of
Conservation and Land Management provides a sound basis for ongoing development of these factors.
The Panel is concerned that consideration is being given to letting contracts in which the annual cut is
solely Grade 1 sawlog. There are concerns that some associated Grade 2 sawlog might be left on the
forest floor. To the extent that this may occur, it constitutes a risk to the sustained yield in that the
monitoring of the actual cut for the period of the Plan could be inaccurate, relative to its definition. In
short, more Grade 1 and 2 sawlog may effectively be being cut than would be apparent from records of
sales.
The Panel believes that it may be preferable that all sawlog contracts be allocated and monitored on the
basis of the volume to 200 mm top diameter combining Grade 1 and Grade 2 for the purposes of yield
regulation and providing for all sawlog harvesting to be based on ‘run-of-bush’ i.e. harvesting all sawlog
products from the forest in whatever ratio it occurs. Differential prices could still be applied for different
log sizes and grades within that definition if required, but it would remove an otherwise unrecognisable
source of error in the regulatory system and assist transparency.
For marri, no solution has yet been found to enable reliable estimation of sawlog volume because of the
difficulties of estimating internal defect and the changing nature of what defines a marri sawlog.
However, whole bole volume is available and very crude estimates from field operations indicate that
there is no problem is sustaining current demands, both sawlog and other.
For wandoo and other species such as blackbutt, estimates of sawlog volumes are available similar to
those for jarrah. No attempt is made to estimate the sustained yield as they are too small to be specifically
regulated on this basis and generally occur in coupes that are predominantly jarrah. Thus the choice of
silviculture and scheduling is regulated by the silvicultural and other settings used or determined for the
jarrah forest types in the case of blackbutt or by the wandoo Silvicultural Guidelines.
8.4
Minimum viable logging volumes
When the volumes to be logged from an area fall below a certain level, the operation can become
uneconomic because the costs of getting the logs to the landing and to the mill are too high. The viable
level varies with factors such as proximity to mill, terrain, distribution of the trees to be logged (clumped
versus individual trees), average log size, whether other products are being removed (e.g. commercial
firewood) and the type of harvesting machinery available. As far as possible, those areas that have clear
limitations because of low volumes and rocky or steep terrain have been removed from consideration as
being inoperable. The Forest Products Commission has indicated that future harvesting contracts will
include the requirement to harvest all areas to a minimum volume of 5 m3/ha grade 1 and 2 sawlogs.
SILVIA has been used to estimate the proportion of each strata that would have a total standing sawlog
volume below this threshold and this area has been excluded from harvest scheduling.
The Panel is satisfied that the allowances made for minimum viable volume per hectare are appropriate
and that the residual risk to sustained yield is small.
Conclusions
The Panel believes that the systems employed to simulate long-term woodflows (FORSCHED and its
supporting systems) are appropriate and robust for the purposes of long term yield projection of jarrah
and karri forests.
The Panel has investigated the operation of the systems and reviewed the derivation of the conversion
factors. It is satisfied that the system produces adequate estimates of utilisable yield for the planning
period.
The Panel notes that there are many factors involved in ensuring that all economically recoverable yield is
harvested from logging coupes. Ongoing development of the procedures and processes used to monitor
utilisation and the effective conversion level is needed. Periodic data needs to be collected across the
range of coupes at the annual or three year level. These should be monitored by the Department and the
Forest Products Commission as a basis for improved management and review.
The Panel is satisfied that the allowances made for minimum viable volume per hectare are appropriate
and that the residual risk to sustained yield is small.
26
8.5
Recommendation
Recommendation 6.
Contracts let by the Forest Products Commission for the supply of sawlogs should be based on the
volume to a 200mm top diameter, using current specifications to the lower limit of Grade 2. This will
improve consistency and transparency of the level of removals against sustained yield calculations..
Within three years the Department of Conservation and Land Management should develop systems to
monitor and report on differences between predicted yields and actual harvest volumes. These should be
reported on annually.
27
9
CALCULATING SUSTAINED YIELDS
9.1
Introduction
The notion of sustained yield has wide appeal and support but little understanding of what is entailed.
Surprisingly to some, it has analogies to a superannuation or pension account in that the notion of
controlling the yield is to moderate and spread the use of the capital to enable the income to be
maintained. Indeed, if the superannuation fund was required to pass on capital to the next generation and
to sustain income over all future generations, the analogy would be still closer.
The principal difference is that a highly capitalised (i.e. predominantly old) forest grows only slowly,
whereas a somewhat lowly capitalised (i.e. younger) forest grows much more rapidly. Very young forest,
on the other hand, grows slowly in terms of the rate of increase in product volume although the rate
increases rapidly as the forest ages up to some maximum, after which it declines. If timber production
were the only goal, sustained yield would simply be about selecting the rotation length which achieved
the highest social net benefit, based on that goal.
But timber production is not the only goal in the State forests and timber reserves of Western Australia.
Other forest uses contribute to social net benefit and cause us to modify that solution so as to recognise
and maintain those other values, not necessarily in their current form and extent, but in a form that is
capable of returning to a similar or better condition over the rotation chosen. Much of the preceding
review of selecting and applying silvicultural treatments is about giving recognition to those trade-offs on
the ground in a particular forest type.
There are also spatial concerns as to where the income and/or capital is to come from at a particular point
in time - this means that scheduling of logging and thinning needs to be moderated spatially, taking
account of species, forest structures and site productivities, and while endeavouring to reduce fire, pest,
soil and water risks. Spatial scheduling at the Regional (Swan, South West and Warren) and whole of
forest levels is therefore required.
9.2
Sustained yield
The sustained yield is calculated by simulating the silvicultural and logging operations on a partly-spatial
basis. The planning model is large and complex and has been refined and, as noted earlier, has been
improved in a number of aspects since the Stage 1 report (Ferguson et al., 2001a). For a particular set of
silvicultural and other options, the planning model enables the predicted values of sawlog and other
volumes to be predicted over time.
Under the CALM Act, timber production from State Forest is required to be managed on a sustained yield
basis. The Interim Proposed Forest Management Plan interprets sustained yield as ‘non-declining yield of
sawlogs’ i.e. the sustained yield is not higher than the average level of wood flow estimated over a
predefined period. In the case of the analysis for the jarrah forest, a common period to 2140 was adopted.
This was based on the period before which major increase in yield will occur from existing regrowth
stands (Figure 9.1). A similar approach was followed for karri although the defined period was shorter.
To facilitate sensitivity testing the same two periods were used for all analyses.
An iterative process is involved because there are minor variations to the options that can be changed to
shift short-term peaks to fill in part or in whole, short-term gaps. For example, logging of a particular area
in advance of bauxite mining can be shifted in time to bring it forward (but not deferred) and so fill a gap
in the pattern of annual volumes otherwise available. Alternatively some thinnings may be deferred but
there are limitations to bringing them forward. The capacity to make such changes to rectify short term
gaps is limited in the time profile and there are fewer opportunities to advance the yield than to defer it.
In all cases, the initial reference option was that specified in Appendix 15 of the Conservation
Commission’s Interim Proposed Forest Management Plan. This option has been referred to as Scenario D.
(The area basis for Scenario D is described in Appendix 1).
9.3
Jarrah and Karri sustained yield options
Two main options each with three variations were run for the Panel to test the trade-offs between the
sustained yield and other values and to compare with Scenario D. Option 1 evaluated a specification of
the proposed Fauna Habitat Zones based on those recommended in Burrows et al, 2002, Option A and
explored sensitivity to variation in dieback spread, rotation length and thinning. Option 2 specifically
tested the potential increase in socio-economic value that might be obtained by access to two tiered and
28
regrowth components within proposed reserves with the same variations in dieback spread, rotation
length and delay to early thinnings. Due to time and resource constraints, it was not possible to
undertake a simulation of the combined effects of the two options taken together.
Dieback spread
In the light of the various reports and research presented, the Panel decided that it could not confirm any
sustained yield option that did not incorporate the recently completed dieback spread and impact
estimates, such was the likely impact on growth, sustained yield and biodiversity values. The significant
magnitude of this impact is illustrated in the reduction in sustained yield and simulated yield flows for
Scenario D (b) (Table 9.1 and Figure 9.1) when compared to Scenario D(a).
Option 1: Alternative Fauna habitat zones
As noted in Chapter 6, alternative specifications for fauna habitat protection have been proposed. The
potential impact on sustained yield of an alternative rule-set (Burrows et al. 2002, Option A) was
examined. The Panel tested this option because it provided an alternative specification recently
recommended by an expert panel. The results (Option 1(a) including dieback) are indicated in Table 9.1.
Option 1b: Delayed thinnings
As noted earlier, the Panel had major reservations concerning the assumption in Scenario D that noncommercial thinning of regrowth jarrah at ages 20 and 50 years represented an economically viable
investment. It therefore examined that all jarrah thinnings would be delayed until an economic sawlog
yield could be achieved. The results (Option 1(b) including dieback) are indicated in Table 9.1.
Option 1c: Shorter rotations
The Panel examined an alternative that reduced the rotation length for jarrah regrowth forest from 200 to
175 years and from 100 to 75 years for some 1,400 ha of pre-1942 karri regrowth.
Option 2: Access to two-tiered and regrowth in proposed reserves.
The Panel notes that there are significant areas of regrowth and two tiered forest in proposed reserves.
Should parts of these areas be made available for timber production they would contribute to increased
socio-economic return and the Panel believes that these might be accessed without compromising oldgrowth values. Because of time constraints, the Panel was only able to evaluate the option that made
available all regrowth and two tiered forest in the new proposed reserves. The Panel does not wish to
claim that this rule-set is optimal; its evaluation was designed to indicate the potential magnitude of the
potential gain in yield. It is assumed that these would be capable of considerable refinement by local
experts if the option were to be further evaluated.
Each of the variants delayed thinning, Option 2(b) and shorter rotations, Option 2(c) were again tested
(Table 9.1) but now relate to the areas of productive forest plus all regrowth and two tiered forest
included in the new proposed reserves.
In the time available, not all the possible combinations of these major changes to Scenario D and Options
1 and 2 could be run, but the Panel is confident that the summary of sustained yield provides a robust
basis for designing a solution that better provides for ecologically sustainable forest management
objectives.
The Panel favours a scenario incorporating a combination of options 1 and 2. However, potential yield
loss from dieback must be incorporated in the final scenario for the Plan. The Panel believes that much of
the thinning of jarrah will be delayed unless markets for these products can be developed or the
Government is prepared to subsidise it and hence the majority of this impact will be felt whatever other
modifications are selected. Shorter rotations should be confined to the more productive jarrah forest (i.e.
other than eastern jarrah) and the inclusion of only that regrowth and two-tiered forest in Dalgarup and
parts of other newly proposed reserves that are readily accessible and of low conservation value.
Local expertise is required to define this option in detail, so we cannot confirm the sustained yield for it.
Nevertheless, it clearly represents a balance that meets almost all of the major underlying concerns and
values. Almost every interest group will claim that it does not achieve its particular goals but the Panel
would argue that, in aggregate, it is likely to achieve a higher level of social net benefit than any one of
the preceding options or of those most favoured by individual interest groups. That is the essence of
trade-offs at the whole-of-forest level
The Panel is satisfied that ample marri resource exists to support a substantial cut of residual wood, if
markets are available, and to supply current sawlog demands.
29
Table 9.1 Estimates of sustained yield for jarrah and karri using Scenario and Panel Options 1 and 2.
Appendix 1 of this report details the area basis for the sustained yield figures provided in this table.
Scenario / Option
Sustained yield (m3/y)
Jarrah
Karri
Scenario D*: Reference scenario
D(a) No allowance for dieback spread
D(b) Allowing for dieback spread
D(c) Allowing for dieback spread, delayed thinnings
D(d) Allowing for dieback spread, shorter rotations
135,000
116,000
111,000
126,000
50,000
50,000
50,000
53,000
126,000
124,000
138,000
52,000
52,000
56,000
Panel Option 1:Alternative fauna habitat zones
1(a) Allowing for dieback spread
1(b) Allowing for dieback spread, delayed thinnings
1(c) Allowing for dieback spread, shorter rotations
Panel Option 2: Access to regrowth/two-tiered areas
2(a) Allowing for dieback spread
139,000
74,000
2(b) Allowing for dieback spread, delayed thinnings
133,000
74,000
2(c) Allowing for dieback spread, shorter rotations
151,000
78,000
* Scenario D is defined in the Interim Proposed Forest Management Plan Appendix 15 and provided to
the Panel as the basis for assessment.
450,000
400,000
350,000
m3 sawlog
300,000
250,000
200,000
150,000
100,000
50,000
39
29
19
09
99
89
49
22
22
22
22
22
21
69
59
49
39
29
19
09
99
89
79
69
59
49
39
29
19
09
79
21
21
21
21
21
21
21
21
21
20
20
20
20
20
20
20
20
20
20
19
99
-
Year
No future dieback spread Future dieback spread
Figure 9.1 Simulated sawlog woodflow of jarrah for Scenario D(b) (no allowance for delayed thinning
or shorter rotations) illustrating the impact of a prediction of simulated autonomous dieback spread.
30
450,000
400,000
350,000
m3 sawlog
300,000
250,000
200,000
150,000
100,000
50,000
99 009 019 029 039 049 059 069 079 089 099 109 119 129 139 149 159 169 179 189 199 209 219 229 239 249
19
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
Year
Sawlog 200mm SED
Sawlog 300mm SED
Figure 9.2 Simulated sawlog woodflow for jarrah for Option 1(a) (allowance for dieback spread, no
allowance for delayed thinning or shorter rotations) to 300mm and 200mm top diameter limit.
350,000
300,000
Karri Even-aged (Rtn 2)
250,000
Karri 2-tier (Rtn 2)
200,000
Karri Even-aged (Rtn 1)
1 50,000
Karri 2-tier (Rtn 1)
1 00,000
Jarrah 2-tier (Rtn 1)
50,000
1 999
201 4
2029
2044
2059
2074
2089
21 04
21 1 9
21 34
21 49
21 64
21 79
21 94
2209
2224
2239
Y ear
Figure 9.3 Simulated sawlog woodflow for karri for Option 1(c) indicating the yield that is sourced from
two- tiered and regowth forest.
31
Conclusions
The Panel is well aware that various levels of allowable cut were proposed in the Draft Forest
Management Plan and in recent Government statements. The role of the Panel is to confirm the levels of
sustained yield appropriate to options that reflect different silvicultural and other settings and so enable
the trade-offs between feasible options to be better evaluated through due processes.
While we have not been able to supply a single tightly defined final option, the implications of our work
are clear and we are confident that the table setting out the levels of sustained yield for various options is
robust, the values are conservative, and that the methodology for analysing operational feasibility is
robust.
Each of the Scenario and Options evaluated provide different levels of contribution to socio-economic
values and biological conservation. The Panel is of the view that a combination of options 1 and 2 will
meet both the biological and other components of ecologically sustainable forest management to a
satisfactory level as outlined in the objectives specified by the Interim Proposed Forest Management Plan.
32
10 OTHER MATTERS
10.1 Improving transparency
The Panel notes the considerable effort put in to improving transparency during the period of the period
of development of the 2004-2013 Forest Management Plan and these are commended.
A wide range of reporting activity and of opportunities for public involvement is noted among the
strategies and actions proposed in the Interim Proposed Forest Management Plan. The Panel notes a
strong emphasis on the reporting of audit results and other compliance measures and the objectives for a
mid-term review and consequent reporting. Effective communication with the broader community is also
needed on more general forestry performance in relation to progress toward achievement of ESFM.
During the review the Panel was provided with statistics relevant to Scenario D that indicated:
•
the area and proportion of the forest that would be impacted by varying degrees of harvest
intensity during the life of the plan,
•
the proportion of the forest that is managed under different rotation lengths, and
•
the proportion of the standing inventory that is expected to be removed by harvesting during the
life of the plan.
Inclusion of such statistics with the final plan would assist transparency and provide a useful perspective
on disturbance due to harvesting.
Modern communication media such as the WWW , the Department of Conservation and Land
Management’s NatureBase website and video provide an excellent basis for timely provision of
information on forest status, achievements and issues reports. The Panel recommends the increased use of
these media to achieve timely communication with the community to increase awareness of issues and
status in respect to forest management.
Nonetheless, increasing public concern and indeed involvement in management of forests through the
stakeholder approach adopted by most governments, produces increasing demands for access to data and
to the systems and methods used to estimate the Sustained Yield.
The Panel notes this increased pressure and urges that new resources be found to support public education
and dissemination (including peer-reviewed publication) programmes.
There is a general lack of publicly available documentation and understanding of the methods and
systems that are used to calculate the Sustained Yield. The Panel re-iterate the concerns expressed in
previous reports and urge that suitably simplified diagrams and explanations be made available via the
World Wide Web and through technical reports. The Panel also urge that, wherever possible, the systems
and models be subject to peer-review through the processes of publication in the international scientific
literature.
10.2 Relationship to the Regional Forest Agreement
Ferguson et al. (1997) provided the background to the assessment of ecologically sustainable forest
management and the associated assessment of the Forest Management System during the assessment
processes leading to the Regional Forest Agreement. Changes to the system at the Commonwealth and
State level have occurred since the assessment was undertaken. Examples include the Regional Forest
Agreement, changes to state legislation (eg. Conservation and Land Management Act 1984) and
commencement of new legislation (eg Environment Protection and Biodiversity Conservation Act 1999
(Cwth), Forest Products Act 2000 and Regional Forest Agreements Act 2002 (Cwth)).
While reference is made to the Environment Protection and Biodiversity Conservation Act 1999 in the
context of threatened species and communities provisions, the Interim Proposed Forest Management Plan
when discussing the framework for the Plan (Chapter 2) does not discuss the legislative framework of the
Plan within the context of the Commonwealth legislation.
Noting our Terms of Reference, the Panel is concerned about how the Regional Forest Agreement relates
to the Forest Management Plan given the establishment of the Regional Forest Agreements Act 2002 and
the consequential obligations resulting from the Western Australian Regional Forest Agreement. This
concern results from how commitments made in the Regional Forest Agreement flow from international
obligations through the Commonwealth legislation (Environment Protection and Biodiversity
Conservation Act 1999; Regional Forest Agreements Act 2002) and national policy (National Forest
Policy Statement) to the State’s Forest Management System and in particular the Management Plan.
Western Australia agreed in the Regional Forest Agreement “to produce and publish a Forest
33
Management Plan to implement the commitments of this Agreement” (Clause 43). The Commonwealth
or other stakeholders may have concerns that the resource base for which Sustained yield is calculated is
not consistent with the resource base commitments of the Regional Forest Agreement, or that Western
Australian forest policy is not consistent with the policy settings and commitments agreed to in the
Regional Forest Agreement. This raises issues concerning the possibility of legally enforceable rights and
obligations that are outside the expertise of the Panel but should be considered by the Conservation
Commission and the Government.
The Panel therefore recommends that Conservation Commission and Government should consider the
possible impact of any legally enforceable rights and obligations associated with the Regional Forest
Agreement that could affect the implementation and legal status of the Forest Management Plan.
10.3 Future determination of sustainable yields
In the calculations of the sustained yield by the Department of Conservation and Land Management, the
assumption is made that non-declining yield is pivotal to the long term sustainability of the forest.
However, reliance on the control of sustained yield of sawlogs alone is a simplistic device when the
intention is to sustain all values. This has been recognised for many years (see Chikumbo et al. 2001) as
evidenced by the increasing conservation and other constraints that have been applied in forest
management over the last decade to ensure that other values are protected or enhanced.
From the social and economic perspective, absolute consistency of timber yield over very long periods
does not necessarily lead to stability of industry. For example, the determination of yield on the basis of a
current product specification in the expectation that this specification will still be relevant in 200 years
time is not very realistic. However the concept of sustained yield as used in the Western Australian
context applies an assumption that the ”grade” of log available to the current generation will be similar
for the generations that follow. While it is recognised that log grade standards to industry may change
over a rotation period the objective applied is one where the quantity of the “quality of sawlogs” used by
the current generation does not decline in the coming generations.
Attempting to forecast a control variable like sustained yield over 200 years will have issues associated
with precision of the long term estimates. Precision declines radically the further the projection is away
from the current date. Planning horizons of 50 to 80 years would be ample, much more realistic, and
would simplify scheduling while focusing more specifically on what are the structural goals and forest
objectives to be achieved at the end of that horizon. However longer-term projections are required to
ensure there is no decrease in yield and other sustainability objectives in the long term (1 to 1.5 rotations).
Specifying the structural goals at the whole-of-forest and structural levels in greater detail for the 50-80
year planning horizon would do much to improve the sustainability of all forest values (including timber).
This should be done in conjunction with the following:
•
Consider the requirements of conservation values as it is done at present through a series of
safeguards (salinity, rare species, CAR reserves etc).
•
Consider similarly the requirements for wood and other non-timber products and services (e.g. water,
recreation).
•
Develop appropriate structural goals at the forest and the landscape level that are required to meet
those needs.
•
Directly monitor and regulate forest structure at the whole-of-forest and landscape levels to ensure
protection of conservation and supply of wood and other non-wood values
•
Develop a maximum timber yield based on an analysis of the capacity to sustain that value over the
planning horizon, subject to achieving the structural goals prescribed above and the explicit
recognition of the trade-offs involved in choosing that yield.
•
Regulate and monitor the timber yield over the period of the Plan (10 years in the present case)
within the requirements imposed by the structural goals.
•
Check the yield strategy against longer-term projections of wood and non-wood values to ensure that
they do not decrease to unacceptable levels to forgo intergenerational options.
The effect of this approach is consistent with what has already been initiated in this report and in the
Interim Proposed Forest Management Plan, although the latter has not yet gone as far as we have
recommended. It involves shifting the emphasis to the sustainability of whole-of-forest and landscape
level structures, and away from a simplistic reliance on non-declining yield of sawlogs as the primary
regulator of sustainability. There is no pre-emptive priority for wood over non-wood values or vice versa.
34
There may need to be an initial array of varying and independent priorities set for all values in the form of
individual structural goals. If a feasible and near-optimal solution cannot be found that satisfies all these
initial structural goals then the nature of the subsequent trade-offs required between goals becomes
transparent. The present process obfuscates these trade-offs but cannot ultimately avoid them, as the
present report shows. This approach is sometimes referred to as ecosystem management, which is an
evolution of the concepts of sustained and sustainable yield (Chikumbo et al. 2001).
Conclusions.
The Panel is of the view that this new approach to the determination of sustained yield could result in
greater benefits to both conservation and socio-economic values than does the rigid application of the
current mechanisms. At the same time it would provide improved transparency of the mechanisms
employed to achieve ecologically sustainable forest management.
The Panel recognises that such an approach would require more rigorous whole-of-forest and landscape
level analyses, which would depend on data sets and approaches that need to be refined and expanded.
These will take some time in their development. Sufficient data are not likely to be available until prior
to the next revision of the Forest Management Plan in 2014. Hence the assumption of non-declining yield
should be retained until an ecosystem management approach can be developed and checked against
ecologically sustainable forest management principles and objectives. Extensive consultation would also
be necessary to build consensus to support the approach.
10.4 Recommendation
Recommendation 7
The Panel recommends that alternative approaches be developed to determine the sustainable yields of a
range of forest values while maintaining critical elements of ecosystem function. This should incorporate
direct approaches to maintain target forest structures, and should be investigated and subjected to
thorough analysis during the life of the plan.
35
11 REFERENCES
Bradshaw,F.J. (2002) Forest Structural Goals: Recommendations to the Department of Conservation and
Land Management.
Burrows, N., Christensen, P., Hopper, S., Ruprecht, J. and Young, J. (2001). Ministerial Condition 11:
Panel Report Part 1 Report to the Department of Conservation and Land Management.
Burrows, N., Christensen, P., Hopper, S., Ruprecht, J. and Young, J. (2002). Towards Ecologically
Sustainable Forest Management in Western Australia: A Review of Draft Jarrah Silviculture Guideline
1/02. Panel Report Part 2 Report for the Conservation Commission of Western Australia.
Chikumbo, O., Spencer, R., Turner, BJ and Davey, SM (2001) Planning and monitoring forest
sustainability: an Australian Perspective. Australian Forestry 64(1): 1-7.
Codd M. (1999). Forest Management Plans 1994-2003: Mid-Term EPA Report on Compliance. Report to
Minister for Environment, Government of Western Australia.
Commonwealth of Australia and the State of Western Australia (1998b). Comprehensive Regional
Assessment, A Regional Forest Agreement for Western Australia. Vol 1. Commonwealth and Western
Australian Regional Forest Agreement Steering Committee, Canberra.
Commonwealth of Australia and the State of Western Australia (1999). Regional Forest Agreement for
the South-West Forest region of Western Australia. Commonwealth and Western Australian Regional
Forest Agreement Steering Committee, Canberra.
Conservation Commission of Western Australia (2002a). Draft Forest Management Plan. Conservation
Commission of Western Australia, Perth.
Conservation Commission of Western Australia (2002b). Analysis of public submissions on the draft
forest management plan of 15 August 2002. Conservation Commission, Perth.
Department of Conservation and Land Management (2000). FORESTCHECK. An integrated system for
monitoring the forests of the south-west Western Australia. CALMScience Division, Internal Concept
Plan, Department of Conservation and Land Management.
Environmental Protection Authority (2001). Protocol for the identification and prioritisation for
management of Phytophthora cinnamomi protectable areas: Dieback Consultative Council: advice to the
Minister for the Environment prepared under section 16(e) of the Environmental Protection Act. Bulletin
1010. Environmental Protection Authority, Perth.
Ferguson, I.F., Adams, M., Brown, M.J., Cork, S.J., Egloff, B., Wilkinson, G. (1997). Assessment of
ecologically sustainable forest management in the south-west of Western Australia. Report of the
Independent Expert Advisory Group. Joint Commonwealth and WA Regional Forest Agreement Steering
Committee.
Ferguson, I. F., Adams, M., Bradshaw, J., Davey, S., McCormack, R., Young, J. (2001a). Calculating
Sustained Yield for the Forest Management Plan (2004-2013): A Preliminary Review. Report to the
Conservation Commission of WA by the Independent Panel. Conservation Commission of Western
Australia, Perth.
Ferguson, I. F., Adams, M., Bradshaw, J., Davey, S., McCormack, R., Young, J. (2001b). Stage 2
Progress report. Calculating Sustained Yield for the Forest Management Plan (2004-2013). Report to the
36
Conservation Commission of WA by the Independent Panel. Conservation Commission of Western
Australia, Perth.
Ferguson, I.F., Gardner, J., Hopper, S., Young, J. (1999). Report to the Minster for Environment by the
Ministerial Advisory Group on Karri and Tingle Management. Ministerial Advisory Group on Karri and
Tingle Management, Perth.
Ferguson I. F. (2002). Maps and Data Assessment. Report on a consultancy for the Conservation
Commission.
Podger, F. D., James, S. H. and Mulcahy, M. J. (1996) Review of Dieback in Western Australia. Volume
1. Report and Recommendations. Report by the Western Australian Dieback Review Panel to the Western
Australian Minister for the Environment, Perth.
Rayner, M.E. (1992). Simulating the growth and yield of regrowth karri (Eucalyptus diversicolor
F.Muell) stands. PhD Thesis The Australian National University. 269 pp.
Strelein, G. J., Sage, L.W., Blankendaal, P. W., van de Sande, A., Moylett, A and Hooper, C. (in prep)
Rate of spread of Phytopthora cinnamomi in jarrah (Eucalyptus marginata) forest of south-western
Australia..
Turner, B. J. (1998). An Appraisal of Methods and Data Used by CALM to Estimate Wood Resource
Yields for the South-west Forest Region of Western Australia. Commonwealth and Western Australian
Regional Forest Agreement Steering Committee, Canberra.
Turner, B., Ferguson, I. and Fitzpatrick, N. (1999). Report by the Expert Panel on the Calculation of a
Sustainable Sawlog Yield for the Jarrah and Karri Forests of WA. Commonwealth and WA RFA Steering
Committee. 16pp.
Water and Rivers Commission (2001). A Review of Stream and River Logging Buffers to ensure their
adequacy in protecting our waterways from salinity, degradation and turbidity – A Policy and Planning
Division Report to the Conservation Commission of WA.
37
38
12 APPENDIX 1
DESCRIPTION OF SCENARIO D AND PANEL OPTIONS 1 AND 2
AREA BASIS
The estimates given of sustained yield for jarrah and karri presented in Table 9.1 were based on areas for
timber production which varied between each of the scenarios as follows:
Scenario D
Consistent with the Interim Proposed Forest Management Plan, areas excluded from timber production
included:
The reserve system as proposed in the Plan (April 2003). This includes all the proposed new national
parks, with their proposed boundaries as progressed to 31 December 2002.
All informal reserves, including all mapped old-growth in State forest.
Areas recommended by the Conservation Commission to be set aside from timber harvesting as formal or
informal reserves following the Review of High Conservation Values in Western Australia’s south-west
forests. This includes the reservation of occurrences of Darling Scarp ecosystem, Dalgarup block, the
southern part of Witchcliffe block and a number of areas that are adjacent or near to new proposed parks.
Areas of less-well-reserved vegetation complexes on State forest that are proposed in the Plan to become
informal reserves. These comprise those vegetation complexes with less than 5% of their estimated preEuropean distribution currently reserved, and those vegetation complexes with 5 to 10% reserved and less
than 15% remaining.
A version of the proposed Fauna Habitat Zones, using a 200 hectare patch size and a 3 kilometre
geographic dispersion. The selection of patches followed the guiding preferences for locating the
predominantly mature forest at the strategic level, whereby patches were aggregated around the informal
reserves such as old growth, streams and DEZ, while attempting to avoid mapped dieback infested sites.
The shape of individual patches would vary as detailed fine-scale design was undertaken to ensure
management features (roads, tracks, creeks, ridge lines) where used as boundaries wherever practicable.
Note that this is one of a number of possible variations in the extent and location of these zones.
Panel Option 1
Excluded from timber production:
The reserve system as proposed in the Plan (April 2003). This includes all the proposed new national
parks, with their proposed boundaries as progressed to 31 December 2002.
All informal reserves, including all mapped old-growth in State forest.
Areas recommended by the Conservation Commission to be set aside from timber harvesting as formal or
informal reserves following the Review of High Conservation Values in Western Australia’s south-west
forests. This includes the reservation of occurrences of Darling Scarp ecosystem, Dalgarup block, the
southern part of Witchcliffe block and a number of areas that are adjacent or near to new proposed parks.
Areas of less-well-reserved vegetation complexes on State forest that are proposed in the Plan to become
informal reserves. These comprise those vegetation complexes with less than 5% of their estimated preEuropean distribution currently reserved, and those vegetation complexes with 5 to 10% reserved and less
than 15% remaining.
Areas of additional mature forest sufficient to ensure that each forest block maintains a minimum of 200
hectares set aside from timber harvesting in each forest block. A total net area of 3,170 hectares of twotiered jarrah was required to meet this criterion following exclusion of the areas listed above.
39
Panel Option 2
Excluded from timber production:
An amended reserve system, in which the net area of non old-growth areas within the new parks proposed
under the Protecting our old-growth forests policy where made available for timber production. The area
made available included both regrowth and two-tiered forests that had been previously cutover.
All informal reserves, including all mapped old-growth in State forest.
Most areas recommended by the Conservation Commission to be set aside from timber harvesting as
formal or informal reserves following the Review of High Conservation Values in Western Australia’s
south-west forests, except Dalgarup block which was made available for timber production. The areas set
aside include the reservation of occurrences of Darling Scarp ecosystem, the southern part of Witchcliffe
block and a number of areas that are adjacent or near to new proposed parks.
Areas of less-well-reserved vegetation complexes on State forest that are proposed in the Plan to become
informal reserves. These comprise those vegetation complexes with less than 5% of their estimated preEuropean distribution currently reserved, and those vegetation complexes with 5 to 10% reserved and less
than 15% remaining.
Note: This option makes no provision for fauna habitat zones as specified in Panel Option 1 or Scenario
D.
Total area The total area of jarrah, karri and wandoo forest available for timber production in State forest
and timber reserves under each of these scenarios, and used in the calculation of sustained yields, was as
follows:
Area (ha) of forest type available under this scenario
Jarrah
Karri
Wandoo
Scenario D
740,500
58,700
36,000
Panel option 1
803,300
61,200
38,000
Panel option 2
868,900
74,100
44,100
Note: Further reductions to the available areas occur during the timber scheduling process as provision is
made for steep slopes, roading and other features.
40
13 APPENDIX 2
SPECIFIC COMMENTS ADDRESSING VIDEO PRESENTATION
Following discussion with members of the Conservation Council, the Council provided a copy of its
recently completed video entitled ‘The Collie Catchment Crisis’. While the Panel lacks first-hand
knowledge of all the areas depicted in the video, individual members are reasonably well acquainted with
the general region and the issues raised.
The Panel makes no comment on the overall picture presented but have instead tried to address a number
of the embedded issues in their current report. We have listed and make comment here on those issues.
1.
2.
3.
4.
5.
If there are clear breaches of logging guidelines (e.g. habitat trees) then these must be
investigated by the Department and if necessary by the Commission. There are clear policies and
guidelines as to the actions required if such breaches are found.
Salinity is a major issue for the south-west. The interim (Proposed) Forest Management Plan
makes clear the scale at which logging impacts will be monitored. Monitoring of the impacts of
logging at smaller scales requires more resources and the Panel is not convinced that further
resources should be directed to the forest when the major issues lie within the agricultural zones.
Wastage is unfortunate but will always be present in commercial logging operations. The Panel
note the concerns about material left in the forest after logging and have made specific
recommendations about the minimum size of logs. More can be done to encourage noncommercial use of material left by logging contractors provided there are the resources available
for supervision.
Collateral damage to understory species such as Banksia, Casuarina, Xanthorrhea is also
inevitable at local scales. The Panel notes that the revised jarrah silvicultural guidelines now
include directives for the greater retention of understory species (Appendix 5 of interim
(Proposed) Forest Management Plan. The Panel has also reviewed the soil damage impacts on
sustained yield and notes that the interim (Proposed) Forest Management Plan makes clear the
use of internationally accepted indicators (e.g. Montreal Process Indicators) to guide
management.
General retention of habitat trees and areas. The Panel notes that there are proposals to increase
the retention of mature habitat. The Panel supports this initiative and makes comment to this
effect in their report.
41
14 APPENDIX 3
Glossary
Adaptive management
The systematic process for continually improving management
policies and practices by learning from the outcomes of
operational programs.
Basal area
The sum of the cross-sectional areas of trees in a given stand
measured at 1.3 metres above the ground. It is usually expressed
as square metres per hectare.
Biological diversity
(Biodiversity) (described in
Conservation and Land
Management Act)
The variability among living biological entities and the
ecosystems and ecological complexes of which those entities are a
part and includes:
(a) diversity within native species and between native species;
(b) diversity of ecosystems; and
(c) diversity of other biodiversity components.
Biological diversity component
(described in Conservation and
Land Management Act)
Includes habitats, ecological communities, genes and ecological
processes
Block
A named administrative subdivision of the forest, varying in size
from about 3,000 to 8,000 hectares.
Bole
The tree trunk from the ground to the major branches supporting
the crown.
Buffer strip
A strip of vegetation retained on the edge of a feature such as a
stream or rock outcrop. Buffer strips can serve a variety of
purposes in the landscape, including protection of the feature
from a disturbing activity, and provide flora and fauna habitat and
aesthetic values.
Catchment
The surface area from which water runs off to a river or any other
collecting reservoir.
Coppice
A shoot (or shoots) arising from adventitious buds at the base of a
woody plant that has been cut near the ground or burnt back.
Coupe
An area of forest that is planned for timber harvesting as a single
unit. It may contain more than one silvicultural objective, such as
a number of discrete gaps or clearfells or a combination of both.
Dieback
In the south-west of Western Australia a disease of plants caused
by infection by the soil-borne organisms of the genus
Phytophthora.
Disturbance
Any range of conditions affecting the condition of a natural area.
Disturbance may be natural (e.g. fire) or human induced (e.g.
timber harvesting).
Diverse ecotype zone
Areas of the forest, generally but not always with little tree cover,
that are identified at the operational management scale to be
protected from activities associated with timber harvesting
because of their importance for the conservation of biodiversity.
They include sedge and herb vegetation, rock outcrops, heath,
42
wetlands, etc.
Ecologically sustainable forest
management (ESFM)
Forest management and use in accordance with the principles
described in section 19(2) of the Conservation and Land
Management Act.
Ecosystem
A community or an assemblage of communities of organisms,
interacting with one another and the environment in which they
live.
Endangered
A taxon is endangered when it is not critically endangered but is
facing a very high risk of extinction in the near future.
Environmental Management
System
A framework for the systematic management of an organisation’s
environmental obligations and targets. Often conforming to a
standard, the most popular being AS/NZS ISO 14001.
Fauna
The animals inhabiting an area; including mammals, birds,
reptiles, amphibians and invertebrates. Usually restricted to
animals occurring naturally and excluding feral or introduced
animals.
With respect to the Wildlife Conservation Act, fauna is:
(a) any animal indigenous to any State or Territory of the
Commonwealth or the territorial waters of the Commonwealth;
(b) any animal that periodically migrates to and lives in any State
or Territory of the Commonwealth or the territorial waters of the
Commonwealth; and
(c) any animal declared as fauna pursuant to subsection (2), and
includes in relation to any such animal –
(d) any class or individual member thereof;
(e) the eggs, larvae or semen;
(f) the carcass, skin, plumage or fur thereof, but does not include
any prescribed animal or prescribed class of animal.
Flora
The plants growing in an area; including flowering and
non-flowering plants, ferns, mosses, lichens, algae and fungi.
Usually restricted to species occurring naturally and excluding
weeds.
With respect to the Wildlife Conservation Act flora is any plant
(including any wildflower, palm, shrub, tree, fern, creeper or
vine) which is: (a) native to the State or (b) declared to be flora
pursuant to subsection (4), and includes any part of flora and all
seeds and spores thereof.
FMIS
Forest Management Information System. The Department of
Conservation and Land Management’s raster-based geographic
information system used to manage and analyse spatial forest
data.
Forest
An area, incorporating all living and non-living components, that
is dominated by trees having usually a single stem and a mature
or potentially mature stand height exceeding two metres and with
existing or potential crown cover of overstorey strata about equal
to or greater than 20 per cent.
Forest ecosystem
An indigenous ecosystem with an overstorey of trees that are
greater than 20 per cent crown cover. These ecosystems should
normally be discriminated at a resolution requiring a mapstandard scale of 1:100,000. Preferably these units should be
defined in terms of floristic composition in combination with
43
substrate and position within the landscape.
Forest operations
Work activities undertaken in the forest to achieve the
management objectives for that forest.
Forest produce
For the purposes of the Conservation and Land Management Act
includes trees, parts of trees, timber, sawdust, chips, firewood,
charcoal, gum, kino, resin, sap, honey, seed, bees-wax, rocks,
stone and soil but, subject to the foregoing, does not in Division 1
of Part VIII include minerals within the meaning of the Mining
Act 1978.
Forest products
For the purposes of the Conservation and Land Management Act
and the Forest Products Act: (1) Subject to subsection (2) trees or
parts of trees; timber, sawdust or chips; charcoal, gum, resin, kino
or sap; and firewood. If they are located on public land or sharefarmed land. (2) When something referred to in subsection (1) has
been removed under contract or arrangement entered into by the
Commission, any residues that remain are not forest products for
the purposes of this (FP Act) Act.
Forest regeneration
The renewal of a forest arising from planting or from seed or the
young plants on a site. The process by which a forest is renewed.
FORSCHED
FORest SCHEDuler. A computer system for scheduling/
simulating yield from forest harvesting operations for one or more
rotations.
Gap
A discrete opening in the overstorey canopy created to reduce
competition to allow seedlings to become established and or
develop.
Guideline
Principles, standards and practices for meeting goals that have
been established as desirable outcomes for management. They can
be quantitative or qualitative.
Habitat
A component of an ecosystem providing food and shelter to a
particular organism.
Heritage
Something inherited from past generations that is valued.
High impact
A term applied to certain forest sites where Phytophthora
cinnamomi has caused or is expected to cause extensive mortality
of jarrah trees.
High rainfall zone
Areas where the average annual rainfall exceeds 1100 millimetres
per year.
Hygiene – in relation to
dieback
Actions that decrease the risk of the pathogen being introduced
spread or intensified.
Intermediate rainfall zone
Areas where the average annual rainfall is between 900 and 1100
millimetres per year.
IOPS
Integrated Operations Planning System. A GIS/database system
for simulating short to medium term plans and operations and
their outcomes over time.
I.R.I.S.
Integrated Resources Information System. A computer system for
storage, processing and retrieval of information for forest
inventory with GIS linkages.
Landscape
The visual elements of both the natural and the built environment
and including landforms, vegetation, waterform, land-use and
architecture.
Lignotuber
A woody swelling formed at the base of some eucalypts that has
the ability to produce new shoots when the existing ones are
44
destroyed.
L.O.I.S.
Logging Operations Information System. A computer system
operated by the Forest Products Commission used to manage log
production and sales records.
Low rainfall zone
Areas where the average annual rainfall is less than 900
millimetres per year.
JARSIM
JARrah SIMulator. A computer system that estimates future
growth of jarrah stands. The system connects to the forest yield
scheduler, FORSCHED.
KARSIM
KARri SIMulator. A computer system that estimates future
growth of karri stands. The system connects to the forest yield
scheduler, FORSCHED.
Monitoring
Regular assessment of a management program and of the
resources being managed, checking that desired outcomes are
achieved, and adjusting the new plan where necessary.
Old-growth forest
Ecologically mature forest where the effects of unnatural
disturbance are now negligible. The definition focuses on forest in
which the upper stratum or overstorey is in a mature to senescent
growth stage.
Patch
A group of trees resulting from a natural regeneration event or a
past management activity such as gap creation and regeneration.
Pest
Troublesome or destructive animals including insects, either
introduced or native.
Prescription
A detailed specification of the objectives, area, procedures and
standards for a task to be undertaken.
Policy
The course of action to be followed to achieve an organisation’s
objectives.
Reserve – conservation
An area set aside primarily for the conservation of natural
ecosystems but which may allow a level of recreation consistent
with the proper maintenance and restoration of the natural
environment.
Reserve – formal
One of the land category categories of national park, nature
reserve, conservation park, or Conservation and Land
Management Act sections 5(1)(g) or 5(1)(h) reserves for the
purpose of conservation.
Reserve – informal
An area set aside for conservation under an approved
management plan; has had opportunity for the public to comment
on changes to reserve boundaries; able to be accurately defined on
a map; and is of an area and design sufficient to sustain the values
it seeks to protect.
Riparian
Pertaining to the banks of streams, rivers or lakes.
Rotation
The planned number of years between the establishment of a crop
and its felling.
Shelterwood system
A jarrah silvicultural system that involves a partial removal from
the overstorey of some mature trees and action to establish
regeneration under the remaining mature trees. When the
regeneration is sufficiently established most of the remaining
mature trees are removed to allow the regeneration to develop.
SILREC
SILvicultural RECord System. A Department of Conservation
and Land Management spatial database for managing and
recording harvesting extent and silvicultural practices.
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SILVIA
SILVicultural Impact Analysis. A computer system for
simulating silvicultural treatment and describes potential yield,
silvicultural options and residual stand outcomes under user
specified silvicultural strategies.
Silviculture
The theory and practice of managing forest establishment,
composition and growth to achieve specified management
objectives.
Specially protected
Those species declared under the Wildlife Conservation Act to be
specially protected because they are deemed otherwise in need of
special protection.
Stand
A group of trees or patch of forest that can be distinguished from
other groups on the basis of size, age, species composition,
condition or other attribute.
Structure
When applied to a forest is the vertical and spatial distribution of
the vegetation.
Sustained yield
The yield that a forest can produce continuously at a given
intensity of management..
Taxa (taxon)
A defined unit (for example, species or genus) in the classification
of plants and animals.
Thinning
A felling made in an immature stand for the purpose of improving
the growth of trees that remain without permanently breaking the
canopy and encouraging regeneration.
Timber harvesting
The cutting, felling, and gathering of forest timber undertaken as
part of a planned sequence of silvicultural activities including the
regeneration of the forest.
Treemarking
The practice of marking trees for retention prior to harvesting in a
forest.
Turbidity
Discolouration of water due to suspended silt or organic matter.
Unprotectable
A term that is applied to forest that will ultimately become
infested with Phytophthora cinnamomi through the autonomous
spread of the disease from adjacent areas.
Vegetation complex
A combination of distinct site vegetation types, usually associated
with a particular geomorphic, climatic, floristic and vegetation
structural association.
Yield
The amount of product produced from the forest by a particular
management strategy.
Yield regulation
The process by which the yield of any product is controlled to
achieve the stipulated levels in a management plan.
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